[BUG?] git fetch -p -t prunes all non-tag refs

Hi,

When the --prune and --tags options are given to git fetch together, all
non-tag refs are pruned because only tags are looked at and when pruning
it appears as if the branches have disappeared and are therefore deleted
locally. Maybe this is an unintentional wanted behavior, but it should
at least be documented that the combination causes this to happen.

    git-1.7.6.2-1.fc15.x86_64

Appears to still be there in master (85e9c7e) from looking at the logs.

--Ben