git-push: forced update of tag shows unabbreviated SHA1

[Johannes Sixt <j.sixt@viscovery.net>]

This is just a cosmetical flaw:

When a tag is changed to point to a new commit, then the tag is pushed to
a repo that still has the old tag, it is correctly pushed, but the old
SHA1 is reported with all 40 digits:

# make upstream repo
$ mkdir A && cd A
$ git init
$ echo a > a; git add a; git commit -m a

# clone, modify, push
$ cd ..
$ git clone A B
$ cd B
$ echo b > a; git commit -a -m b
$ git push file://$PWD/../A

# tag old state in upstream
$ cd ../A
$ git tag -m T T HEAD~1

# tag new state in clone (same name) and force-push tag
$ cd ../B
$ git tag -m Tclone T
$ git push -f file://$PWD/../A refs/tags/*:refs/tags/*
Counting objects: 1, done.
Unpacking objects: 100% (1/1), done.
Writing objects: 100% (1/1), 160 bytes, done.
Total 1 (delta 0), reused 0 (delta 0)
To file:///home/jsixt/tmp/foo/B/../A
 + 639669ce44f84417f30842c622064827dda01461...475e55f T -> T (forced update)

Notice that the original SHA1 is not abbreviated.

-- Hannes