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
HGMERGE=true; export HGMERGE
echo % init
hg init
echo % commit
echo 'a' > a
hg ci -A -m test -u nobody -d '1 0'
echo % annotate -c
hg annotate -c a
echo % annotate -d
hg annotate -d a
echo % annotate -n
hg annotate -n a
echo % annotate -u
hg annotate -u a
echo % annotate -cdnu
hg annotate -cdnu a
cat <<EOF >>a
a
a
EOF
hg ci -ma1 -d '1 0'
hg cp a b
hg ci -mb -d '1 0'
cat <<EOF >> b
b
b
b
EOF
hg ci -mb2 -d '2 0'
echo % annotate b
hg annotate b
echo % annotate -nf b
hg annotate -nf b
hg up -C 2
cat <<EOF >> b
b
c
b
EOF
hg ci -mb2.1 -d '2 0'
hg merge
hg ci -mmergeb -d '3 0'
echo % annotate after merge
hg annotate -nf b
hg up -C 1
hg cp a b
cat <<EOF > b
a
z
a
EOF
hg ci -mc -d '3 0'
hg merge
cat <<EOF >> b
b
c
b
EOF
echo d >> b
hg ci -mmerge2 -d '4 0'
echo % annotate after rename merge
hg annotate -nf b
echo % linkrev vs rev
hg annotate -r tip a