Added check for .git directory in current, before wasting time querying git....

Added check for .git directory in current, before wasting time querying git. This saves seconds on my pc.

plugins/git/git.plugin.zsh

@@ -73,12 +73,14 @@ alias gsd='git svn dcommit'
 # Usage example: git pull origin $(current_branch)
 #
 function current_branch() {
+  if [ ! -d .git ]; then return; fi
   ref=$(git symbolic-ref HEAD 2> /dev/null) || \
   ref=$(git rev-parse --short HEAD 2> /dev/null) || return
   echo ${ref#refs/heads/}
 }
 
 function current_repository() {
+  if [ ! -d .git ]; then return; fi
   ref=$(git symbolic-ref HEAD 2> /dev/null) || \
   ref=$(git rev-parse --short HEAD 2> /dev/null) || return
   echo $(git remote -v | cut -d':' -f 2)