treemanifest: extract parse method from constructor
When we start to lazily load submanifests, it will be useful to be
able to create an treemanifest instance before manifest data gets
parsed into it. To prepare for this, extract the parsing code from
treemanifest's constructor to a separate method.
#require serve
$ hg init test
$ cd test
$ cat > .hg/hgrc <<EOF
> [extensions]
> # this is only necessary to check that the mapping from
> # interhg to websub works
> interhg =
>
> [websub]
> issues = s|Issue(\d+)|<a href="http://bts.example.org/issue\1">Issue\1</a>|
>
> [interhg]
> # check that we maintain some interhg backwards compatibility...
> # yes, 'x' is a weird delimiter...
> markbugs = sxbugx<i class="\x">bug</i>x
> EOF
$ touch foo
$ hg add foo
$ hg commit -d '1 0' -m 'Issue123: fixed the bug!'
$ hg serve -n test -p $HGPORT -d --pid-file=hg.pid -A access.log -E errors.log
$ cat hg.pid >> $DAEMON_PIDS
log
$ "$TESTDIR/get-with-headers.py" localhost:$HGPORT "rev/tip" | grep bts
<div class="description"><a href="http://bts.example.org/issue123">Issue123</a>: fixed the <i class="x">bug</i>!</div>
errors
$ cat errors.log
$ cd ..