phabricator: change "readpatch" to be more flexible
Previously, `readpatch` and `querydrev` take a same `params` and `stack`
parameters. This patch changes `readpatch` so it takes the output of
`querydrev`, not the input of `querydrev`. This makes the code more
flexible and cleaner.
Differential Revision: https://phab.mercurial-scm.org/D124
To run the tests, do:
cd tests/
python run-tests.py
See https://mercurial-scm.org/wiki/WritingTests for
more information on writing tests.