Update way to get branch name in git repo.

.bashrc

@@ -55,11 +55,12 @@ __prompt_git_status() {
     }
 
     # Add the branch or a no commits marker.
-    BRANCH="$(git describe --contains --all HEAD 2>/dev/null)"
-    if [[ -n "$BRANCH" ]]; then
-      GIT_PROMPT+="$BRANCH"
-    else
+    BRANCH="$(git rev-parse --abbrev-ref HEAD 2>/dev/null)"
+    if [[ "$BRANCH" == "HEAD" ]]; then
       GIT_PROMPT+="!NO COMMITS!"
+      unset BRANCH
+    else
+      GIT_PROMPT+="$BRANCH"
     fi
 
     # Add upstream status.