contrib/editmerge

crecord: fix issue when backgrounding editor would leave artefact

Before this patch:
- if a user was entering a commit message after having ran the curses
interface
- and then uses ctrl-z, followed by fg to put the editor in the
background/foreground
- then the curses interface would leave artefact on the screen of
the editor, making entering the commit message a difficult task

This happened because ncurses registers a signal handler for SIGTSTP and
does not restore the original signal handler after running.
More info at:
http://stackoverflow.com/questions/31440392/
curses-wrapper-messing-up-terminal-after-background-foreground-sequence/
31441709#31441709

This patch restores the original value of the signal handler after
running the curses interface and therefore fixes this issue.
It don't know how to add a test for this issue, I tested the scenario
above manually and it works correctly with the patch.

#!/usr/bin/env bash
# A simple script for opening merge conflicts in the editor.
# Use the following Mercurial settings to enable it.
#
# [ui]
# merge = editmerge
#
# [merge-tools]
# editmerge.args=$output
# editmerge.check=changed
# editmerge.premerge=keep

FILE=$1

getlines() {
  grep -n "<<<<<<" $FILE | cut -f1 -d:
}

# editor preference loosely based on http://mercurial.selenic.com/wiki/editor
# hg showconfig is at the bottom though, since it's slow to run (0.15 seconds)
ED=$HGEDITOR
if [ "$ED" = "" ] ; then
  ED=$VISUAL
fi
if [ "$ED" = "" ] ; then
  ED=$EDITOR
fi
if [ "$ED" = "" ] ; then
  ED=$(hg showconfig ui.editor)
fi
if [ "$ED" = "" ] ; then
  echo "merge failed - unable to find editor"
  exit 1
fi

if [ "$ED" = "emacs" ] || [ "$ED" = "nano" ] || [ "$ED" = "vim" ] ; then
  FIRSTLINE=$(getlines | head -n 1)
  PREVIOUSLINE=""

  # open the editor to the first conflict until there are no more
  # or the user stops editing the file
  while [ ! "$FIRSTLINE" = "" ] && [ ! "$FIRSTLINE" = "$PREVIOUSLINE" ] ; do
    $ED +$FIRSTLINE $FILE
    PREVIOUSLINE=$FIRSTLINE
    FIRSTLINE=$(getlines | head -n 1)
  done
else
  $ED $FILE
fi

# get the line numbers of the remaining conflicts
CONFLICTS=$(getlines | sed ':a;N;$!ba;s/\n/, /g')
if [ ! "$CONFLICTS" = "" ] ; then
  echo "merge failed - resolve the conflicts (line $CONFLICTS) then use 'hg resolve --mark'"
  exit 1
fi

exit 0