graphlog: fix --follow FILE and relative paths
The situation is complicated because filelog() revset uses a match object in
relpath mode while follow() revset interprets the filename as a manifest entry.
from mercurial.hg import parseurl
def testparse(url, branch=[]):
print '%s, branches: %r' % parseurl(url, branch)
testparse('http://example.com/no/anchor')
testparse('http://example.com/an/anchor#foo')
testparse('http://example.com/no/anchor/branches', branch=['foo'])
testparse('http://example.com/an/anchor/branches#bar', branch=['foo'])
testparse('http://example.com/an/anchor/branches-None#foo', branch=None)
testparse('http://example.com/')
testparse('http://example.com')
testparse('http://example.com#foo')