localrepo: make it possible to pass multiple path elements to join and wjoin
This makes join and wjoin behave in the same way as os.path.join. That is, it
makes it possible to pass more than one path element to them.
Note that the first path element is still required, as it was before this patch,
and as is the case for os.path.join.
running: init test1
result: None
running: add foo
result: 0
running: commit -m commit1 -d 2000-01-01 foo
result: None
running: commit -m commit2 -d 2000-01-02 foo
result: None
running: log -r 0
changeset: 0:0e4634943879
user: test
date: Sat Jan 01 00:00:00 2000 +0000
summary: commit1
result: None
running: log -r tip
changeset: 1:45589e459b2e
tag: tip
user: test
date: Sun Jan 02 00:00:00 2000 +0000
summary: commit2
result: None