Fixed a bashism with the use of $RANDOM in hgeditor.

The variable $RANDOM is not POSIX so a portable /bin/sh may not define
it.  When creating a directory with a random name it's better to use
mktemp, which, even though is not POSIX, exists in common Unixes
including Linux, OpenBSD, FreeBSD and MacOS X.

hgeditor

@@ -27,10 +27,10 b' cleanup_exit() {'
 trap "cleanup_exit" 0 # normal exit
 trap "exit 255" HUP INT QUIT ABRT TERM
 
-HGTMP="${TMPDIR-/tmp}/hgeditor.$RANDOM.$RANDOM.$RANDOM.$$"
-(umask 077 && mkdir "$HGTMP") || {
-    echo "Could not create temporary directory! Exiting." 1>&2
-    exit 1
+HGTMP=$(mktemp -d ${TMPDIR-/tmp}/hgeditor.XXXXXX)
+[ x$HGTMP != x -a -d $HGTMP ] || {
+  echo "Could not create temporary directory! Exiting." 1>&2
+  exit 1
 }
 
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