--- a/.hgeditor	Thu Dec 22 13:39:14 2016 +0800
+++ b/.hgeditor	Thu Dec 22 13:40:29 2016 +0800
@@ -13,11 +13,11 @@
 trap "cleanup_exit" 0 # normal exit
 trap "exit 255" HUP INT QUIT ABRT TERM
 
-HGTMP=$(mktemp -d ${TMPDIR-/tmp}/hgeditor.XXXXXX)
-[ x$HGTMP != x -a -d $HGTMP ] || {
-  echo "Could not create temporary directory! Exiting." 1>&2
-  exit 1
-}
+HGTMP=$(mktemp -d "${TMPDIR-/tmp}/hgeditor.XXXXXX")
+if [ -z "$HGTMP" ] || ! [ -d "$HGTMP" ]; then
+    echo "Could not create temporary directory! Exiting." 1>&2
+    exit 1
+fi
 
 (
     grep '^HG: \(changed\|added\|removed\)' "$1" | cut -d ' ' -f 3- | while read changed; do
@@ -29,7 +29,7 @@
 
 MD5=$(which md5sum 2>/dev/null) || \
     MD5=$(which md5 2>/dev/null)
-[ -x "${MD5}" ] && CHECKSUM=`${MD5} "$HGTMP/msg"`
+[ -x "${MD5}" ] && CHECKSUM=$(${MD5} "$HGTMP/msg")
 if [ -s "$HGTMP/diff" ]; then
     vim -f "+e $HGTMP/diff" '+set buftype=help filetype=diff' "+vsplit $HGTMP/msg" '+setlocal spell' || exit $?
 else