setdiscovery: document algorithms used
This is taken from:
http://programmers.stackexchange.com/questions/208998
And modified slightly.
Put here definitions of blacklists for run-tests.py
Create a file per blacklist. Each file should list the names of tests that you
want to be skipped.
File names are meant to be used as targets for run-tests.py --blacklist
option.
Lines starting with # are ignored. White spaces are stripped.
e.g. if you create a blacklist/example file containing:
test-hgrc
# some comment
test-help
then calling "run-tests.py --blacklist blacklists/example" will exclude
test-hgrc and test-help from the list of tests to run.