match: add basic wrapper for boolean function
This serves as a generic wrapper for fileset predicates. In future patches,
a fileset expression will be mapped to a tree of matchers for a better support
of match attributes such as visitdir(). For example,
$ hg debugwalk -v 'set:contrib/** and binary()'
* matcher:
<intersectionmatcher
m1=<patternmatcher patterns='(?:contrib/.*$)'>,
m2=<predicatematcher pred=binary>>
...
https://bz.mercurial-scm.org/842
$ hg init
$ echo foo > a
$ hg ci -Ama
adding a
$ hg up -r0000
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ echo bar > a
Should issue new head warning:
$ hg ci -Amb
adding a
created new head
$ hg up -r0000
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ echo stuffy > a
Should not issue new head warning:
$ hg ci -q -Amc
$ hg up -r0000
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ echo crap > a
$ hg branch testing
marked working directory as branch testing
(branches are permanent and global, did you want a bookmark?)
Should not issue warning:
$ hg ci -q -Amd