Rev 428419380b9f introduced some sed -r tests, but -r is only available on GNU
sed, while BSD sed uses -E. Better to use old-style regular expressions, that
way the tests work on all sed variants.
collections: direct child repos only
paths *: direct child repos only (like collections)
paths **: recursive discovery
When ** is used, the mq repository (if any) is also shown.
This feature somehow duplicates [collections] but it is simpler to use and has
less issues under Windows where using absolute path as configuration file key
is not supported.
Suggested by Dirkjan Ochtman <dirkjan@ochtman.nl>
