revsets: let p1() and p2() return parents of working dir
This patch makes the 'set' argument to revset functions p1() and p2()
optional. If no argument is given, p1() and p2() return the first or second
parent of the working directory.
If the working directory is not an in-progress merge (no 2nd parent), p2()
returns the empty set. For a checkout of the null changeset, both p1() and
p2() return the empty set.
$ HGENCODING=utf-8
$ export HGENCODING
$ try() {
> hg debugrevspec --debug $@
> }
$ log() {
> hg log --template '{rev}\n' -r "$1"
> }
$ hg init repo
$ cd repo
$ try 'p1()'
('func', ('symbol', 'p1'), None)
-1
$ try 'p2()'
('func', ('symbol', 'p2'), None)
null revision
$ log 'p1()'
$ log 'p2()'
working dir with a single parent
$ echo a > a
$ hg ci -Aqm0
$ log 'p1()'
0
$ log 'p2()'
merge in progress
$ echo b > b
$ hg ci -Aqm1
$ hg up -q 0
$ echo c > c
$ hg ci -Aqm2
$ hg merge -q
$ log 'p1()'
2
$ log 'p2()'
1