fix backtrace printed when cannot get lock.
change lock error handling code so exceptions have useful info and
exception handling in one place.
add test case for when cannot get lock.
#!/bin/sh
hg init
echo foo > foo
hg add foo
hg commit -m1 -d"0 0"
echo "# should show copy"
hg copy foo bar
hg debugstate|grep '^copy'
echo "# shouldn't show copy"
hg commit -m2 -d"0 0"
hg debugstate|grep '^copy'
echo "# should match"
hg debugindex .hg/data/foo.i
hg debugrename bar
echo bleah > foo
echo quux > bar
hg commit -m3 -d"0 0"
echo "# should not be renamed"
hg debugrename bar
hg copy -f foo bar
echo "# should show copy"
hg debugstate|grep '^copy'
hg commit -m3 -d"0 0"
echo "# should show no parents for tip"
hg debugindex .hg/data/bar.i
echo "# should match"
hg debugindex .hg/data/foo.i
hg debugrename bar
echo "# should show no copies"
hg debugstate|grep '^copy'
exit 0