Version: 2d26a030a05d92fbb7489d62cfb7759b8f045335 (ToT on 4/26/2016)
OS: OS X El Capitan 10.11.4

What steps will reproduce the problem?
(1) In some directory with plenty of space, do "fetch chromium"
(2) When it errors with "gclient sync" returning non-zero exit status, re-execute gclient sync.

What is the expected output?

A long wait, and then a clean chromium checkout ready to build.

What do you see instead?

A failure in generating the XCode projects because of duplicate mksnapshot entries.  See below.


rdsmith-macbookpro:../Sandboxen/testchrome $ fetch chromium
Running: gclient root
Running: gclient config --spec 'solutions = [
  {
    "managed": False,
    "name": "src",
    "url": "https://chromium.googlesource.com/chromium/src.git",
    "custom_deps": {},
    "deps_file": ".DEPS.git",
    "safesync_url": "",
  },
]
'
Running: gclient sync
Error: Command '/usr/bin/python src/build/gyp_chromium --running-as-hook' returned non-zero exit status 1 in /Users/rdsmith/Sandboxen/testchrome
Traceback (most recent call last):
  File "/Users/rdsmith/Sandboxen/depot_tools/fetch.py", line 346, in <module>
    sys.exit(main())
  File "/Users/rdsmith/Sandboxen/depot_tools/fetch.py", line 341, in main
    return run(options, spec, root)
  File "/Users/rdsmith/Sandboxen/depot_tools/fetch.py", line 335, in run
    return checkout.init()
  File "/Users/rdsmith/Sandboxen/depot_tools/fetch.py", line 142, in init
    self.run_gclient(*sync_cmd)
  File "/Users/rdsmith/Sandboxen/depot_tools/fetch.py", line 76, in run_gclient
    return self.run(cmd_prefix + cmd, **kwargs)
  File "/Users/rdsmith/Sandboxen/depot_tools/fetch.py", line 66, in run
    return subprocess.check_output(cmd, **kwargs)
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/subprocess.py", line 573, in check_output
    raise CalledProcessError(retcode, cmd, output=output)
subprocess.CalledProcessError: Command '('gclient', 'sync')' returned non-zero exit status 2
rdsmith-macbookpro:../Sandboxen/testchrome $ gclient sync
Syncing projects: 100% (64/64), done.

________ running '/usr/bin/python src/build/landmines.py' in '/Users/rdsmith/Sandboxen/testchrome'

________ running '/usr/bin/python src/tools/remove_stale_pyc_files.py src/android_webview/tools src/build/android src/gpu/gles2_conform_support src/infra src/ppapi src/printing src/third_party/catapult src/third_party/closure_compiler/build src/tools' in '/Users/rdsmith/Sandboxen/testchrome'

________ running '/usr/bin/python src/build/download_nacl_toolchains.py --mode nacl_core_sdk sync --extract' in '/Users/rdsmith/Sandboxen/testchrome'

________ running '/usr/bin/python src/build/android/play_services/update.py download' in '/Users/rdsmith/Sandboxen/testchrome'

________ running '/usr/bin/python src/build/linux/sysroot_scripts/install-sysroot.py --running-as-hook' in '/Users/rdsmith/Sandboxen/testchrome'

________ running '/usr/bin/python src/build/vs_toolchain.py update' in '/Users/rdsmith/Sandboxen/testchrome'

________ running '/usr/bin/python src/build/mac_toolchain.py' in '/Users/rdsmith/Sandboxen/testchrome'
Using local toolchain.

________ running '/usr/bin/python src/third_party/binutils/download.py' in '/Users/rdsmith/Sandboxen/testchrome'

________ running '/usr/bin/python src/tools/clang/scripts/update.py --if-needed' in '/Users/rdsmith/Sandboxen/testchrome'
Updating Clang to 267383-1...
Clang is already up to date.

________ running '/usr/bin/python src/build/util/lastchange.py -o src/build/util/LASTCHANGE' in '/Users/rdsmith/Sandboxen/testchrome'

________ running '/usr/bin/python src/build/util/lastchange.py --git-hash-only -s src/third_party/WebKit -o src/build/util/LASTCHANGE.blink' in '/Users/rdsmith/Sandboxen/testchrome'

________ running 'download_from_google_storage --no_resume --platform=win32 --no_auth --bucket chromium-gn -s src/buildtools/win/gn.exe.sha1' in '/Users/rdsmith/Sandboxen/testchrome'
The current platform doesn't match "win32", skipping.

________ running 'download_from_google_storage --no_resume --platform=darwin --no_auth --bucket chromium-gn -s src/buildtools/mac/gn.sha1' in '/Users/rdsmith/Sandboxen/testchrome'
0> File src/buildtools/mac/gn exists and SHA1 matches. Skipping.
Success!
Downloading 1 files took 0.014553 second(s)

________ running 'download_from_google_storage --no_resume --platform=linux* --no_auth --bucket chromium-gn -s src/buildtools/linux64/gn.sha1' in '/Users/rdsmith/Sandboxen/testchrome'
The current platform doesn't match "linux*", skipping.

________ running 'download_from_google_storage --no_resume --platform=win32 --no_auth --bucket chromium-clang-format -s src/buildtools/win/clang-format.exe.sha1' in '/Users/rdsmith/Sandboxen/testchrome'
The current platform doesn't match "win32", skipping.

________ running 'download_from_google_storage --no_resume --platform=darwin --no_auth --bucket chromium-clang-format -s src/buildtools/mac/clang-format.sha1' in '/Users/rdsmith/Sandboxen/testchrome'
0> File src/buildtools/mac/clang-format exists and SHA1 matches. Skipping.
Success!
Downloading 1 files took 0.012053 second(s)

________ running 'download_from_google_storage --no_resume --platform=linux* --no_auth --bucket chromium-clang-format -s src/buildtools/linux64/clang-format.sha1' in '/Users/rdsmith/Sandboxen/testchrome'
The current platform doesn't match "linux*", skipping.

________ running 'download_from_google_storage --no_resume --platform=darwin --no_auth --bucket chromium-libcpp -s src/third_party/libc++-static/libc++.a.sha1' in '/Users/rdsmith/Sandboxen/testchrome'
0> File src/third_party/libc++-static/libc++.a exists and SHA1 matches. Skipping.
Success!
Downloading 1 files took 0.019827 second(s)

________ running 'download_from_google_storage --no_resume --platform=win32 --no_auth --bucket chromium-luci -d src/tools/luci-go/win64' in '/Users/rdsmith/Sandboxen/testchrome'
The current platform doesn't match "win32", skipping.

________ running 'download_from_google_storage --no_resume --platform=darwin --no_auth --bucket chromium-luci -d src/tools/luci-go/mac64' in '/Users/rdsmith/Sandboxen/testchrome'
0> File src/tools/luci-go/mac64/isolate exists and SHA1 matches. Skipping.
Success!
Downloading 1 files took 0.042021 second(s)

________ running 'download_from_google_storage --no_resume --platform=linux* --no_auth --bucket chromium-luci -d src/tools/luci-go/linux64' in '/Users/rdsmith/Sandboxen/testchrome'
The current platform doesn't match "linux*", skipping.

________ running 'download_from_google_storage --no_resume --platform=linux* --no_auth --bucket chromium-eu-strip -s src/build/linux/bin/eu-strip.sha1' in '/Users/rdsmith/Sandboxen/testchrome'
The current platform doesn't match "linux*", skipping.

________ running 'download_from_google_storage --no_resume --platform=win32 --no_auth --bucket chromium-drmemory -s src/third_party/drmemory/drmemory-windows-sfx.exe.sha1' in '/Users/rdsmith/Sandboxen/testchrome'
The current platform doesn't match "win32", skipping.

________ running '/usr/bin/python src/build/get_syzygy_binaries.py --output-dir=src/third_party/syzygy/binaries --revision=1a6e67fecbd5363c425107b2dee4be8f23dbea35 --overwrite' in '/Users/rdsmith/Sandboxen/testchrome'
INFO:get_syzygy_binaries.py:Output directory does not exist, skipping cleanup.

________ running '/usr/bin/python src/build/get_syzygy_binaries.py --output-dir=src/third_party/kasko/binaries --revision=266a18d9209be5ca5c5dcd0620942b82a2d238f3 --resource=kasko.zip --resource=kasko_symbols.zip --overwrite' in '/Users/rdsmith/Sandboxen/testchrome'
INFO:get_syzygy_binaries.py:Unexpected output directory, skipping cleanup.

________ running 'download_from_google_storage --no_resume --platform=win32 --directory --recursive --no_auth --num_threads=16 --bucket chromium-apache-win32 src/third_party/apache-win32' in '/Users/rdsmith/Sandboxen/testchrome'
The current platform doesn't match "win32", skipping.

________ running 'download_from_google_storage --no_resume --platform=linux* --extract --no_auth --bucket chromium-fonts -s src/third_party/blimp_fonts/font_bundle.tar.gz.sha1' in '/Users/rdsmith/Sandboxen/testchrome'
The current platform doesn't match "linux*", skipping.

________ running '/usr/bin/python src/third_party/instrumented_libraries/scripts/download_binaries.py' in '/Users/rdsmith/Sandboxen/testchrome'

________ running '/usr/bin/python src/build/android/download_doclava.py' in '/Users/rdsmith/Sandboxen/testchrome'

________ running '/usr/bin/python src/build/gyp_chromium --running-as-hook' in '/Users/rdsmith/Sandboxen/testchrome'
Updating projects from gyp files...
Traceback (most recent call last):
  File "src/build/gyp_chromium", line 12, in <module>
    execfile(__file__ + '.py')
  File "src/build/gyp_chromium.py", line 357, in <module>
    sys.exit(main())
  File "src/build/gyp_chromium.py", line 344, in main
    gyp_rc = gyp.main(args)
  File "/Users/rdsmith/Sandboxen/testchrome/src/tools/gyp/pylib/gyp/__init__.py", line 538, in main
    return gyp_main(args)
  File "/Users/rdsmith/Sandboxen/testchrome/src/tools/gyp/pylib/gyp/__init__.py", line 523, in gyp_main
    generator.GenerateOutput(flat_list, targets, data, params)
  File "/Users/rdsmith/Sandboxen/testchrome/src/tools/gyp/pylib/gyp/generator/xcode.py", line 1141, in GenerateOutput
    AddSourceToTarget(source, type, pbxp, xct)
  File "/Users/rdsmith/Sandboxen/testchrome/src/tools/gyp/pylib/gyp/generator/xcode.py", line 507, in AddSourceToTarget
    xct.SourcesPhase().AddFile(source)
  File "/Users/rdsmith/Sandboxen/testchrome/src/tools/gyp/pylib/gyp/xcodeproj_file.py", line 1855, in AddFile
    file_ref = file_group.AddOrGetFileByPath(path, hierarchical)
  File "/Users/rdsmith/Sandboxen/testchrome/src/tools/gyp/pylib/gyp/xcodeproj_file.py", line 1304, in AddOrGetFileByPath
    hierarchical)
  File "/Users/rdsmith/Sandboxen/testchrome/src/tools/gyp/pylib/gyp/xcodeproj_file.py", line 1304, in AddOrGetFileByPath
    hierarchical)
  File "/Users/rdsmith/Sandboxen/testchrome/src/tools/gyp/pylib/gyp/xcodeproj_file.py", line 1299, in AddOrGetFileByPath
    assert group_ref.__class__ == PBXGroup
AssertionError
Error: Command '/usr/bin/python src/build/gyp_chromium --running-as-hook' returned non-zero exit status 1 in /Users/rdsmith/Sandboxen/testchrome
Hook '/usr/bin/python src/build/gyp_chromium --running-as-hook' took 126.81 secs
rdsmith-macbookpro:../Sandboxen/testchrome $ 


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Note that this happens with existing checkouts as well; I tried it with a new checkout just to rule out configuration problems.