Allow to push a tag that points to a non-commit object

This was fixed in 2.11.1 with change I013c75db9 but was then
inadvertently reverted by change If4a2375db which was included
in 2.11.2 and 2.11.3.

Redo the original fix.

Bug: Issue 3328
Change-Id: I85e5e1afc65b1408acd0754f6adbdb6742928aaf
1 file changed