tests/test-pull-pull-corruption

util._matcher: speed up regexp matching.

In 4babaa52badf, Benoit made a change that substantially slows matching
when a big .hgignore file is in play, because it calls into the regexp
matching engine potentially hundreds of times per file to be matched.

I've partly rolled back his change, so that we only call into the matcher
once per file, but preserved the ability to report a meaningful error
message if there's a syntax error in the regexp.

#!/bin/sh
#
# Corrupt an hg repo with two pulls.
#

# create one repo with a long history
hg init source1
cd source1
touch foo
hg add foo
for i in 1 2 3 4 5 6 7 8 9 10; do
    echo $i >> foo
    hg ci -m $i
done
cd ..

# create one repo with a shorter history
hg clone -r 0 source1 source2
cd source2
echo a >> foo
hg ci -m a
cd ..

# create a third repo to pull both other repos into it
hg init corrupted
cd corrupted
# use a hook to make the second pull start while the first one is still running
echo '[hooks]' >> .hg/hgrc
echo 'prechangegroup = sleep 5' >> .hg/hgrc

# start a pull...
hg pull ../source1 &

# ... and start another pull before the first one has finished
sleep 1
hg pull ../source2 2>/dev/null

# see the result
wait
hg verify