Don't show the diff in hgeditor if there are no changes in file contents.

hgeditor

@@ -1,67 +1,71 b''
 #!/bin/sh
 #
 # This is an example of using HGEDITOR to automate the signing of
 # commits and so on.
 
 # change this to one to turn on GPG support
 SIGN=0
 
 # If you want to pass your favourite editor some other parameters
 # only for Mercurial, modify this:
 case "${EDITOR}" in
     "")
         EDITOR="vi"
         ;;
     emacs)
         EDITOR="$EDITOR -nw"
         ;;
     gvim|vim)
         EDITOR="$EDITOR -f -o"
         ;;
 esac
 
 
 HGTMP=""
 cleanup_exit() {
     rm -rf "$HGTMP"
 }
 
 # Remove temporary files even if we get interrupted
 trap "cleanup_exit" 0 # normal exit
 trap "exit 255" 1 2 3 6 15 # HUP INT QUIT ABRT TERM
 
 HGTMP="${TMPDIR-/tmp}/hgeditor.$RANDOM.$RANDOM.$RANDOM.$$"
 (umask 077 && mkdir "$HGTMP") || {
     echo "Could not create temporary directory! Exiting." 1>&2
     exit 1
 }
 
 (
     cd "`hg root`"
     grep '^HG: changed' "$1" | cut -b 13- | while read changed; do
         hg diff "$changed" >> "$HGTMP/diff"
     done
 )
 
 echo > "$HGTMP/msg"
 if [ "$SIGN" == "1" ]; then
     MANIFEST=`grep '^HG: manifest hash' "$1" | cut -b 19-`
     echo -e "\nmanifest hash: $MANIFEST" >> "$HGTMP/msg"
 fi
 grep -vE '^(HG: manifest hash .*)?$' "$1" >> "$HGTMP/msg"
 
 CHECKSUM=`md5sum "$HGTMP/msg"`
-$EDITOR "$HGTMP/msg" "$HGTMP/diff" || exit $?
+if [ -s "$HGTMP/diff" ]; then
+    $EDITOR "$HGTMP/msg" "$HGTMP/diff" || exit $?
+else
+    $EDITOR "$HGTMP/msg" || exit $?
+fi
 echo "$CHECKSUM" | md5sum -c >/dev/null 2>&1 && exit 13
 
 if [ "$SIGN" == "1" ]; then
     {
         head -n 1 "$HGTMP/msg"
         echo
         grep -v "^HG:" "$HGTMP/msg" | gpg -t -a -u "${HGUSER}" --clearsign
     } > "$HGTMP/msg.gpg" && mv "$HGTMP/msg.gpg" "$1"
 else
     mv "$HGTMP/msg" "$1"
 fi
 
 exit $?