Restore previous behavior of GetSha1ForSvnRev, so unit tests pass.

Review URL: https://chromiumcodereview.appspot.com/11148019

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@161909 0039d316-1c4b-4281-b951-d872f2087c98

gclient_scm.py

@@ -590,7 +590,8 @@ class GitWrapper(SCMWrapper):
             print('Running git svn fetch. This might take a while.\n')
           scm.GIT.Capture(['svn', 'fetch'], cwd=self.checkout_path)
         try:
-          sha1 = scm.GIT.GetSha1ForSvnRev(cwd=self.checkout_path, rev=rev)
+          sha1 = scm.GIT.GetBlessedSha1ForSvnRev(
+              cwd=self.checkout_path, rev=rev)
         except gclient_utils.Error, e:
           sha1 = e.message
           print('\nWarning: Could not find a git revision with accurate\n'

scm.py

@@ -402,10 +402,23 @@ class GIT(object):
     if not GIT.IsGitSvn(cwd=cwd):
       return None
     try:
-      git_svn_rev = GIT.Capture(
+      output = GIT.Capture(['svn', 'find-rev', 'r' + str(rev)], cwd=cwd)
-          ['svn', 'find-rev', 'r' + str(rev)], cwd=cwd).rstrip()
+      return GIT.ParseGitSvnSha1(output)
+    except subprocess2.CalledProcessError:
+      return None
+
+  @staticmethod
+  def GetBlessedSha1ForSvnRev(cwd, rev):
+    """Returns a git commit hash from the master branch history that has
+    accurate .DEPS.git and git submodules.  To understand why this is more
+    complicated than a simple call to `git svn find-rev`, refer to:
+
+    http://www.chromium.org/developers/how-tos/git-repo
+    """
+    git_svn_rev = GIT.GetSha1ForSvnRev(cwd, rev)
     if not git_svn_rev:
       return None
+    try:
       output = GIT.Capture(
           ['rev-list', '--ancestry-path', '--reverse',
           '--grep', 'SVN changes up to revision [0-9]*',

tests/gclient_scm_test.py

@@ -1096,11 +1096,12 @@ class ManagedGitWrapperTestCaseMox(BaseTestCase):
     gclient_scm.scm.GIT.GetGitSvnHeadRev(cwd=self.base_path).MultipleTimes(
         ).AndReturn(2)
 
-    self.mox.StubOutWithMock(gclient_scm.scm.GIT, 'GetSha1ForSvnRev', True)
+    self.mox.StubOutWithMock(
+        gclient_scm.scm.GIT, 'GetBlessedSha1ForSvnRev', True)
     # r1 -> first fake hash, r3 -> second fake hash.
-    gclient_scm.scm.GIT.GetSha1ForSvnRev(cwd=self.base_path, rev='1'
+    gclient_scm.scm.GIT.GetBlessedSha1ForSvnRev(cwd=self.base_path, rev='1'
         ).AndReturn(self.fake_hash_1)
-    gclient_scm.scm.GIT.GetSha1ForSvnRev(cwd=self.base_path, rev='3'
+    gclient_scm.scm.GIT.GetBlessedSha1ForSvnRev(cwd=self.base_path, rev='3'
         ).MultipleTimes().AndReturn(self.fake_hash_2)
 
     # Ensure that we call git svn fetch if our LKGR is > the git-svn HEAD rev.

tests/scm_unittest.py

@@ -79,6 +79,7 @@ class GitWrapperTestCase(BaseSCMTestCase):
         'current_version',
         'FetchUpstreamTuple',
         'GenerateDiff',
+        'GetBlessedSha1ForSvnRev',
         'GetBranch',
         'GetBranchRef',
         'GetCheckoutRoot',