sync: skip bloat check if fresh sync

Initial syncs won't have accumulated any garbage.

Bug: 379111283
Change-Id: I04b2ecde3e33f1f055038861a2705ab6aabb36d1
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/536083
Commit-Queue: Gavin Mak <gavinmak@google.com>
Reviewed-by: Mike Frysinger <vapier@google.com>
Tested-by: Gavin Mak <gavinmak@google.com>

project.py

@@ -2579,7 +2579,7 @@ class Project:
         effective_depth = (
             self.clone_depth or self.manifest.manifestProject.depth
         )
-        if effective_depth == 1:
+        if effective_depth == 1 and git_require((2, 23, 0)):
             cmd.append("--no-auto-gc")
 
         if not verbose:

subcmds/sync.py

@@ -1437,6 +1437,12 @@ later is required to fix a server side protocol bug.
         run 'git count-objects -v' and warn if the repository is accumulating
         excessive pack files or garbage.
         """
+        # We only care about bloated projects if we have a git version that
+        # supports --no-auto-gc (2.23.0+) since what we use to disable auto-gc
+        # in Project._RemoteFetch.
+        if not git_require((2, 23, 0)):
+            return
+
         projects = [p for p in projects if p.clone_depth]
         if not projects:
             return
@@ -2104,7 +2110,8 @@ later is required to fix a server side protocol bug.
                 "experience, sync the entire tree."
             )
 
-        self._CheckForBloatedProjects(all_projects, opt)
+        if existing:
+            self._CheckForBloatedProjects(all_projects, opt)
 
         if not opt.quiet:
             print("repo sync has finished successfully.")