run-tests: use a list comprehension instead of map

tests: fix omit path list All directories need a trailing asterisk. Otherwise the files are not excluded from coverage.

commands: partial backout of fbb68b382040

phase: add metavar to -r help text

phase: the REV argument can be repeated

commands: no need to rename merge and phases on import

phase: there is actually no -C option

phase: use standard syntax for command line flags We don't mark them as literal text and we mention the short option the first time we talk about a given flag.

phase: fix RST markup (use ``...`` for literal text)

phase: lowercase option help, rephrase slightly