gclient: Give priority to URL over paths when specifying revisions.

e.g. when specifying both '--revision src@<something>' and
'--revision <src_gerrit_repo>@<some_gerrit_ref>', gclient will sync to
'<some_gerrit_ref>' instead of '<something>'.

This is useful when specifying which gerrit change to patch, which
should take priority over other revision specifications.

Bug: chromium:643346
Change-Id: Ibc21ede355b56e4da966f38f144ce6f6f1743403
Reviewed-on: https://chromium-review.googlesource.com/949981
Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>
Reviewed-by: Aaron Gable <agable@chromium.org>

gclient.py

@@ -962,8 +962,9 @@ class Dependency(gclient_utils.WorkItem, DependencySettings):
     parsed_url = self.LateOverride(self.url)
     file_list = [] if not options.nohooks else None
     revision_override = revision_overrides.pop(self.name, None)
-    if not revision_override and parsed_url:
-      revision_override = revision_overrides.get(parsed_url.split('@')[0], None)
+    if parsed_url:
+      revision_override = revision_overrides.pop(
+          parsed_url.split('@')[0], revision_override)
     if run_scm and parsed_url:
       # Create a shallow copy to mutate revision.
       options = copy.copy(options)
@@ -2599,9 +2600,12 @@ def CMDsync(parser, args):
                     dest='revisions', metavar='REV', default=[],
                     help='Enforces revision/hash for the solutions with the '
                          'format src@rev. The src@ part is optional and can be '
-                         'skipped. -r can be used multiple times when .gclient '
-                         'has multiple solutions configured and will work even '
-                         'if the src@ part is skipped.')
+                         'skipped. You can also specify URLs instead of paths '
+                         'and gclient will find the solution corresponding to '
+                         'the given URL. If a path is also specified, the URL '
+                         'takes precedence. -r can be used multiple times when '
+                         '.gclient has multiple solutions configured, and will '
+                         'work even if the src@ part is skipped.')
   parser.add_option('--with_branch_heads', action='store_true',
                     help='Clone git "branch_heads" refspecs in addition to '
                          'the default refspecs. This adds about 1/2GB to a '

tests/gclient_smoketest.py

@@ -514,6 +514,24 @@ class GClientSmokeGIT(GClientSmokeBase):
         ['sync', '-v', '-v', '-v', '--revision', 'refs/changes/1212'])
     self.assertEquals(0, rc)
 
+  def testSyncUrl(self):
+    if not self.enabled:
+      return
+    self.gclient(['config', self.git_base + 'repo_1', '--name', 'src'])
+    self.gclient([
+        'sync', '-v', '-v', '-v',
+        '--revision', 'src/repo2@%s' % self.githash('repo_2', 1),
+        '--revision', '%srepo_2@%s' % (self.git_base, self.githash('repo_2', 2))
+    ])
+    # repo_2 should've been synced to @2 instead of @1, since URLs override
+    # paths.
+    tree = self.mangle_git_tree(('repo_1@2', 'src'),
+                                ('repo_2@2', 'src/repo2'),
+                                ('repo_3@2', 'src/repo2/repo_renamed'))
+    tree['src/git_hooked1'] = 'git_hooked1'
+    tree['src/git_hooked2'] = 'git_hooked2'
+    self.assertTree(tree)
+
   def testRunHooks(self):
     if not self.enabled:
       return