Update _CheckForImmutableRevision to use git rev-list

_CheckForImmutableRevision is used to see if repo can
skip fetching a project, but 'git rev-parse' with partial
clone does a data fetch to accomplish this.

Changed to use: 'git rev-list -1 --missing=allow-any <SHA>^0' which
checks the local ref without fetching from the server first.

Bug: [google internal] b/179477822

Testing:
- Unit tests
- Verified init/sync working on aosp-master
- Verified wwith a pinned manifest that local ref check works (no fetch)

Change-Id: If327b893c6658421f41df1f58c337f53b4c60ce6
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/296142
Reviewed-by: Dan Willemsen <dwillemsen@google.com>
Tested-by: Ian Kasprzak <iankaz@google.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/project.py b/project.py
index 17c75b4d..9c7d9ec1 100644
--- a/project.py
+++ b/project.py
@@ -438,6 +438,7 @@ class RemoteSpec(object):
     self.orig_name = orig_name
     self.fetchUrl = fetchUrl
 
+
 class Project(object):
   # These objects can be shared between several working trees.
   shareable_files = ['description', 'info']
@@ -1927,7 +1928,8 @@ class Project(object):
     try:
       # if revision (sha or tag) is not present then following function
       # throws an error.
-      self.bare_git.rev_parse('--verify', '%s^0' % self.revisionExpr)
+      self.bare_git.rev_list('-1', '--missing=allow-any',
+                             '%s^0' % self.revisionExpr, '--')
       return True
     except GitError:
       # There is no such persistent revision. We have to fetch it.