preprocess_for_goma failing on 8 builders

Builders failed on: 
- Android Builder: 
  https://build.chromium.org/p/chromium.perf/builders/Android%20Builder
- Android Compile: 
  https://build.chromium.org/p/chromium.perf/builders/Android%20Compile
- Android arm64 Builder: 
  https://build.chromium.org/p/chromium.perf/builders/Android%20arm64%20Builder
- Android arm64 Compile: 
  https://build.chromium.org/p/chromium.perf/builders/Android%20arm64%20Compile
- Linux Builder: 
  https://build.chromium.org/p/chromium.perf/builders/Linux%20Builder
- Mac Builder: 
  https://build.chromium.org/p/chromium.perf/builders/Mac%20Builder
- Win Builder: 
  https://build.chromium.org/p/chromium.perf/builders/Win%20Builder
- Win x64 Builder: 
  https://build.chromium.org/p/chromium.perf/builders/Win%20x64%20Builder

Error:

compiler proxy (pid=811) status: http://127.0.0.1:8088 error: failed to connect to backend servers
Traceback (most recent call last):
  File "/b/c/goma_client/goma_ctl.py", line 2455, in <module>
    sys.exit(main())
  File "/b/c/goma_client/goma_ctl.py", line 2450, in main
    goma.Dispatch(sys.argv[1:])
  File "/b/c/goma_client/goma_ctl.py", line 1114, in Dispatch
    self._action_mappings.get(args[0], self._DefaultAction)()
  File "/b/c/goma_client/goma_ctl.py", line 801, in _RestartCompilerProxy
    self._StartCompilerProxy()
  File "/b/c/goma_client/goma_ctl.py", line 621, in _StartCompilerProxy
    self._GenericStartCompilerProxy(ensure=False)
  File "/b/c/goma_client/goma_ctl.py", line 618, in _GenericStartCompilerProxy
    raise Error('Failed to start compiler_proxy successfully.')
__main__.Error: Failed to start compiler_proxy successfully.
step returned non-zero exit code: 1