merge: rename p1 to wctx in manifestmerge
This is always a workingctx, and this name is more in line with other
functions in this module.
hg debuginstall
$ hg debuginstall
checking encoding (ascii)...
checking Python lib (*lib*)... (glob)
checking installed modules (*mercurial)... (glob)
checking templates (*mercurial?templates)... (glob)
checking commit editor...
checking username...
no problems detected
hg debuginstall with no username
$ HGUSER= hg debuginstall
checking encoding (ascii)...
checking Python lib (*lib*)... (glob)
checking installed modules (*mercurial)... (glob)
checking templates (*mercurial?templates)... (glob)
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]