From the other issue:

It looks like there used to be some vestigial support for CYGWIN to run the tools updater when running gclient under CYGWIN (but not MINGW): https://chromium.googlesource.com/chromium/tools/depot_tools/+/master/update_depot_tools#31

We could make this work for mingw as well, but it still wouldn't solve this problem if the user has their versions of these tools on PATH ahead of depot_tools.

Unfortunately, it looks like some tools (like 'find') are being found by the update bat scripts (e.g. it's expecting the builtin)

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/tools/depot_tools.git/+/02ef57e288c377d577bbecc0574e91e8ff94e051

commit 02ef57e288c377d577bbecc0574e91e8ff94e051
Author: iannucci@chromium.org <iannucci@chromium.org>
Date: Wed Mar 30 01:46:41 2016

Make git binary tools auto update on mingw

R=dnj@chromium.org, pkasting@chromium.org
BUG= 598941 

Review URL: https://codereview.chromium.org/1845493003 .

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@299556 0039d316-1c4b-4281-b951-d872f2087c98

[modify] https://crrev.com/02ef57e288c377d577bbecc0574e91e8ff94e051/bootstrap/win/win_tools.bat
[modify] https://crrev.com/02ef57e288c377d577bbecc0574e91e8ff94e051/update_depot_tools

This seems to be working now, though we discovered that there are (at least) 3 different ways to run bash, and only 2 of them work, so I'm going to make a followup fix to add a warning if we detect the third case.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/tools/depot_tools.git/+/cf231ddddbeaa1309bc5cef400443011677e3e77

commit cf231ddddbeaa1309bc5cef400443011677e3e77
Author: iannucci@chromium.org <iannucci@chromium.org>
Date: Wed Mar 30 02:45:15 2016

Add warning when running gclient under MSYS shell.

R=dnj@chromium.org, pkasting@chromium.org
BUG= 598941 

Review URL: https://codereview.chromium.org/1847433002

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@299559 0039d316-1c4b-4281-b951-d872f2087c98

[modify] https://crrev.com/cf231ddddbeaa1309bc5cef400443011677e3e77/update_depot_tools

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/tools/depot_tools.git/+/02ef57e288c377d577bbecc0574e91e8ff94e051

commit 02ef57e288c377d577bbecc0574e91e8ff94e051
Author: iannucci@chromium.org <iannucci@chromium.org>
Date: Wed Mar 30 01:46:41 2016

Make git binary tools auto update on mingw

R=dnj@chromium.org, pkasting@chromium.org
BUG= 598941 

Review URL: https://codereview.chromium.org/1845493003 .

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@299556 0039d316-1c4b-4281-b951-d872f2087c98

[modify] https://crrev.com/02ef57e288c377d577bbecc0574e91e8ff94e051/bootstrap/win/win_tools.bat
[modify] https://crrev.com/02ef57e288c377d577bbecc0574e91e8ff94e051/update_depot_tools

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/tools/depot_tools.git/+/cf231ddddbeaa1309bc5cef400443011677e3e77

commit cf231ddddbeaa1309bc5cef400443011677e3e77
Author: iannucci@chromium.org <iannucci@chromium.org>
Date: Wed Mar 30 02:45:15 2016

Add warning when running gclient under MSYS shell.

R=dnj@chromium.org, pkasting@chromium.org
BUG= 598941 

Review URL: https://codereview.chromium.org/1847433002

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@299559 0039d316-1c4b-4281-b951-d872f2087c98

[modify] https://crrev.com/cf231ddddbeaa1309bc5cef400443011677e3e77/update_depot_tools