--- a/.bash_prompt	Sat Oct 29 10:59:26 2016 +0800
+++ b/.bash_prompt	Sat Oct 29 10:59:51 2016 +0800
@@ -78,6 +78,7 @@
         local REV=${PARENTS[0]}
         local MERGEREV=${PARENTS[1]}
 
+        if [[ $REV = '-1' ]] ; then REV='' ; fi
         if [[ $BRANCH = 'default' ]] ; then BRANCH='' ; fi
         if [[ $MERGEREV ]] ; then MERGEREV="+$MERGEREV" ; fi
         case "$COMMIT" in