subcmds: Use repo logger

Bug: b/292704435
Change-Id: Ia3a45d87fc0bf0d4a1ba53050d9c3cd2dba20e55
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/386236
Reviewed-by: Jason Chang <jasonnc@google.com>
Commit-Queue: Aravind Vasudevan <aravindvasudev@google.com>
Tested-by: Aravind Vasudevan <aravindvasudev@google.com>

subcmds/selfupdate.py

@@ -13,15 +13,18 @@
 # limitations under the License.
 
 import optparse
-import sys
 
 from command import Command
 from command import MirrorSafeCommand
 from error import RepoExitError
+from repo_logging import RepoLogger
 from subcmds.sync import _PostRepoFetch
 from subcmds.sync import _PostRepoUpgrade
 
 
+logger = RepoLogger(__file__)
+
+
 class SelfupdateError(RepoExitError):
     """Exit error for failed selfupdate command."""
 
@@ -66,7 +69,7 @@ need to be performed by an end-user.
         else:
             result = rp.Sync_NetworkHalf()
             if result.error:
-                print("error: can't update repo", file=sys.stderr)
+                logger.error("error: can't update repo")
                 raise SelfupdateError(aggregate_errors=[result.error])
 
             rp.bare_git.gc("--auto")