git-p4: handle p4 branches and labels containing shell chars

git-p4: handle p4 branches and labels containing shell chars

Don't use shell expansion when detecting branches, as it will
fail if the branch name contains a shell metachar. Similarly
for labels.

Add additional test for branches with shell metachars.

Signed-off-by: Luke Diamand <redacted>
Acked-by: Pete Wyckoff <redacted>
Signed-off-by: Junio C Hamano <redacted>