revlog: allow reverse iteration with revlog.revs
We often need to perform rev iteration in reverse order. This
changeset makes it possible to do so, in order to avoid costly reverse
or reversed() calls later.
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]