git-merge: fix "fix confusion between tag and branch" for real
git-merge: fix "fix confusion between tag and branch" for real

An earlier commit 3683dc5a broke the merge message generation with
a careless use of && where it was not needed, breaking the merge
message for cases where non branches are given.

Signed-off-by: Junio C Hamano <dc50d1021234060e53ec42a77d526afa2fe07479@cox.net>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git