revsets: let parents() return parents of working dir
This patch makes the 'set' argument to revset function parents() optional.
Like p1() and p2(), if no argument is given, returns the parent(s) of the
working directory.
Morally equivalent to 'p1()+p2()', as expected.
hg debuginstall
$ hg debuginstall
Checking encoding (ascii)...
Checking installed modules (*/mercurial)... (glob)
Checking templates...
Checking patch...
Checking commit editor...
Checking username...
No problems detected
hg debuginstall with no username
$ HGUSER= hg debuginstall
Checking encoding (ascii)...
Checking installed modules (*/mercurial)... (glob)
Checking templates...
Checking patch...
Checking commit editor...
Checking username...
no username supplied (see "hg help config")
(specify a username in your configuration file)
1 problems detected, please check your install!
[1]