load git-prompt only in bash

shrc

@@ -1021,7 +1021,7 @@ for f in /usr/share/git/git-prompt.sh \
     /opt/local/share/git-core/git-prompt.sh \
     /opt/local/share/doc/git-core/contrib/completion/git-prompt.sh
 do
-    test -r "$f" && . "$f" && break
+    test -r "$f" && inbash && . "$f" && break
 done
 GIT_PS1_SHOWDIRTYSTATE=t
 GIT_PS1_SHOWUPSTREAM=t