tests/test-issue672

templatekw: change {file_copies} behaviour, add {file_copies_switch}

{file_copies} template now displays file copies with or without the --copies
switch being set. A new {file_copies_switch} template implements the former
behaviour.

#!/bin/sh

# 0-2-4
#  \ \ \
#   1-3-5
#
# rename in #1, content change in #4.

hg init t
cd t

touch 1
touch 2
hg commit -Am init  # 0

hg rename 1 1a
hg commit -m rename # 1

hg co -C 0
echo unrelated >> 2
hg ci -m unrelated1 # 2

hg merge --debug 1
hg ci -m merge1 # 3

hg co -C 2
echo hello >> 1
hg ci -m unrelated2 # 4

hg co -C 3
hg merge -y --debug 4

hg co -C 4
hg merge -y --debug 3