sync: make --prune the default

If a remote deletes a ref, and it points to an object that doesn't
exist locally, we can get into a bad state, and the only way for the
user to recover is to run `repo sync --prune` (and to know that is
the option they need).  The error message is not helpful:

fatal: bad object refs/remotes/cros/firmware-zork-13421.B-master
error: https://chromium.googlesource.com/chromiumos/platform/ec did not send all necessary objects

This situation can also come up when the remote renames refs in a
UNIX FS incompatible way.  For example, replacing refs/heads/foo
with refs/heads/foo/bar.

Also add a --no-prune option for users to disable the behavior.

Bug: https://issuetracker.google.com/203366450
Change-Id: Icf45d838a10938feb091d29800f7e49240830ec3
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/322956
Reviewed-by: Andrew Lamb <andrewlamb@google.com>
Tested-by: Mike Frysinger <vapier@google.com>

1 files changed, 7 insertions, 2 deletions

diff --git a/subcmds/sync.py b/subcmds/sync.py
index d4e302ac..2e6afccc 100644
--- a/subcmds/sync.py
+++ b/subcmds/sync.py
@@ -249,8 +249,10 @@ later is required to fix a server side protocol bug.
     p.add_option('--retry-fetches',
                  default=0, action='store', type='int',
                  help='number of times to retry fetches on transient errors')
-    p.add_option('--prune', dest='prune', action='store_true',
-                 help='delete refs that no longer exist on the remote')
+    p.add_option('--prune', action='store_true',
+                 help='delete refs that no longer exist on the remote (default)')
+    p.add_option('--no-prune', dest='prune', action='store_false',
+                 help='do not delete refs that no longer exist on the remote')
     if show_smart:
       p.add_option('-s', '--smart-sync',
                    dest='smart_sync', action='store_true',
@@ -927,6 +929,9 @@ later is required to fix a server side protocol bug.
       if None in [opt.manifest_server_username, opt.manifest_server_password]:
         self.OptionParser.error('both -u and -p must be given')
 
+    if opt.prune is None:
+      opt.prune = True
+
   def Execute(self, opt, args):
     if opt.jobs:
       self.jobs = opt.jobs