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
$ hg init
$ echo This is file a1 > a
$ hg add a
$ hg commit -m "commit #0"
$ ls
a
$ echo This is file b1 > b
$ hg add b
$ hg commit -m "commit #1"
$ hg co 0
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
B should disappear
$ ls
a