test-walk: add more tests for -I/-X
We had very limited testing of -I and -X, especially when combined
with plain file patterns and with each other. This adds some more
protection against regressions as upcoming patches modify the matcher
code. (Originally meant for my own upcoming patches, but now I know
drgott will be sending some patches soon.)
The only noteworthy cases seems to be that both of
hg debugwalk -Xbeans/black beans/black
hg debugwalk -Xbeans beans/black
walk the file. I would personally have expected the -X to trump. I
don't care enough to change it, but I also think it's fair if some
future commit changes the behavior.