update: fix typo/stale comment to match code
The comment about "obsolete.background" seems to have been about
obsolete.foreground ever since it was introduced in a59e575c6ff8
(update: allow dirty update to foreground (successors), 2013-04-16),
so let's change it.
$ hg init
$ echo 123 > a
$ hg add a
$ hg commit -m "first" a
$ mkdir sub
$ echo 321 > sub/b
$ hg add sub/b
$ hg commit -m "second" sub/b
$ cat sub/b
321
$ hg co 0
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ cat sub/b 2>/dev/null || echo "sub/b not present"
sub/b not present
$ test -d sub || echo "sub not present"
sub not present