extdiff: do single file diffs from the wc with no copy
Extdiff was always making a temporary directory and copying files even when not required. This change makes extdiff avoid the copy when diffing a single file that lives in the wc. This lets external diff tools edit the working copy file directly. It also lets other extensions resuse the functions in extdiff and get in-place diffs.
#!/bin/sh
echo "[extensions]" >> $HGRCPATH
echo "extdiff=" >> $HGRCPATH
hg init a
cd a
echo a > a
echo b > b
hg add
# should diff cloned directories
hg extdiff -o -r $opt
echo "[extdiff]" >> $HGRCPATH
echo "cmd.falabala=echo" >> $HGRCPATH
echo "opts.falabala=diffing" >> $HGRCPATH
hg falabala
hg help falabala
hg ci -d '0 0' -mtest1
echo b >> a
hg ci -d '1 0' -mtest2
# should diff cloned files directly
hg falabala -r 0:1
# test diff during merge
hg update 0
echo c >> c
hg add c
hg ci -m "new branch" -d '1 0'
hg update -C 1
hg merge tip
# should diff cloned file against wc file
hg falabala > out || echo "diff-like tools yield a non-zero exit code"
# cleanup the output since the wc is a tmp directory
sed 's:\(.* \).*\(\/test-extdiff\):\1[tmp]\2:' out