init: change --manifest-depth default to 1

Most users do not care about the manifest history in .repo/manifests/.
Let's change the default to 1 so things work smoothly for most people
most of the time.  For the rare folks who want the full history, they
can add --manifest-depth=0 to their `repo init`.

This has no effect on existing checkouts.

Spot checking Android & CrOS manifests shows significant speedups.
Full history can take O(10's seconds) to O(minutes) while depth of 1
takes constant time of O(~5 seconds).

Bug: 468033850
Change-Id: I4b8ed62a8a636babcc5226552badb69600d0c353
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/535481
Tested-by: Mike Frysinger <vapier@google.com>
Commit-Queue: Mike Frysinger <vapier@google.com>
Reviewed-by: Gavin Mak <gavinmak@google.com>

man/repo-init.1

@@ -1,5 +1,5 @@
 .\" DO NOT MODIFY THIS FILE!  It was generated by help2man.
-.TH REPO "1" "September 2024" "repo init" "Repo Manual"
+.TH REPO "1" "December 2025" "repo init" "Repo Manual"
 .SH NAME
 repo \- repo init - manual page for repo init
 .SH SYNOPSIS
@@ -53,7 +53,7 @@ create a git checkout of the manifest repo
 .TP
 \fB\-\-manifest\-depth\fR=\fI\,DEPTH\/\fR
 create a shallow clone of the manifest repo with given
-depth (0 for full clone); see git clone (default: 0)
+depth (0 for full clone); see git clone (default: 1)
 .SS Manifest (only) checkout options:
 .TP
 \fB\-c\fR, \fB\-\-current\-branch\fR

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:

repo

@@ -129,7 +129,7 @@ if not REPO_REV:
 BUG_URL = "https://issues.gerritcodereview.com/issues/new?component=1370071"
 
 # increment this whenever we make important changes to this script
-VERSION = (2, 54)
+VERSION = (2, 61)
 
 # increment this if the MAINTAINER_KEYS block is modified
 KEYRING_VERSION = (2, 3)
@@ -325,7 +325,7 @@ def InitParser(parser):
     group.add_option(
         "--manifest-depth",
         type="int",
-        default=0,
+        default=1,
         metavar="DEPTH",
         help="create a shallow clone of the manifest repo with "
         "given depth (0 for full clone); see git clone "

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.")