Fallback to full sync when depth enabled fetch of a sha1 fails

In sha1 mode, when depth is enabled, syncing the revision from
upstream may not work because some servers only allow fetching
named refs. Fetching a specific sha1 may result in an error like
'server does not allow request for unadvertised object'. In this
case, attempt a full sync with depth disabled.

Bug: 410825502
Change-Id: If51bcf18b877cd9491706f5bc3d6fd13c0c3d4f3
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/468282
Commit-Queue: Kaushik Lingarkar <kaushikl@qti.qualcomm.com>
Tested-by: Kaushik Lingarkar <kaushikl@qti.qualcomm.com>
Reviewed-by: Gavin Mak <gavinmak@google.com>
Reviewed-by: Mike Frysinger <vapier@google.com>

project.py

@@ -2755,6 +2755,14 @@ class Project:
                 # field; it doesn't exist, thus abort the optimization attempt
                 # and do a full sync.
                 break
+            elif depth and is_sha1 and ret == 1:
+                # In sha1 mode, when depth is enabled, syncing the revision
+                # from upstream may not work because some servers only allow
+                # fetching named refs. Fetching a specific sha1 may result
+                # in an error like 'server does not allow request for
+                # unadvertised object'. In this case, attempt a full sync
+                # without depth.
+                break
             elif ret < 0:
                 # Git died with a signal, exit immediately.
                 break