"git commit -v" for hg (Mecurial) (appends the diff of the changeset to the hg message)

.hgrc

[ui]
# Usage: Assuming that you've saved hgeditor as ~/.mercurial/hgeditor
editor = ~/.mercurial/hgeditor

hgeditor

#!/bin/sh
# Append the diff to hg commit, like git commit -v
# Based on hgeditor downloaded on 19 July 2014 from http://mercurial.selenic.com/wiki/hgeditor
# Completely rewritten though.
#
# Known issue: Does not work for hg commit --amend
#
# Created by Rob Wu <rob@robwu.nl> (https://robwu.nl)

HGTMP=""
cleanup_exit() {
    rm -rf "$HGTMP"
}

# Remove temporary files even if we get interrupted
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
}

DIFFLINE='# ------------------------ >8 ------------------------'

sed 's/^HG:/#HG:/' "$1" > "$HGTMP/msg"

>>/"$HGTMP/msg" cat <<DIFFHEADER
$DIFFLINE
# Do not touch the line above.
# Everything below will be removed.
DIFFHEADER

(
    # GNU grep 
    grep -oP '^HG: (added|changed|removed)\K.+' "$1" | while read changed; do
        "$HG" diff --git "$changed" >> "$HGTMP/msg"
    done
)

MD5=$(which md5sum 2>/dev/null) || \
    MD5=$(which md5 2>/dev/null)
[ -x "${MD5}" ] && CHECKSUM=`${MD5} "$HGTMP/msg"`


case "${EDITOR}" in
    "")
        vi "$HGTMP/msg" +'set syntax=diff' || $?
        ;;
    emacs)
        $EDITOR -nw "$HGTMP/msg" || exit $?
        ;;
    gvim|vim)
        $EDITOR -f -o "$HGTMP/msg" +'set syntax=diff' || exit $?
        ;;
esac

[ -x "${MD5}" ] && (echo "$CHECKSUM" | ${MD5} -c >/dev/null 2>&1 && exit 13)

# Escape DIFFLINE, just in case anyone ever wants to put metacharacters in it.
DIFFLINE=$(sed 's/[\*\.]/\\&/g' <<<"$DIFFLINE")
sed "0,/$DIFFLINE/p; d" "$HGTMP/msg" | \
  sed "/$DIFFLINE/d" | \
  sed "s/^#HG:/HG:/" \
  > "$1"

exit $?