git-pull: refuse default merge without branch.*.merge
git-pull: refuse default merge without branch.*.merge

Everybody hated the pull behaviour of merging the first branch
listed on remotes/* file (or remote.*.fetch config) into the
current branch.  This finally corrects that UI wart by
forbidding "git pull" without an explicit branch name on the
command line or branch.$current.merge for the current branch.

The matching change to git-clone was made to prepare the default
branch.*.merge entry for the primary branch some time ago.

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