directaccess: make sure gethashsymbols does not return rev numbers
With "hg log -r 1 -r 2 -r 3", gethashsymbols will get the following tree:
('func', ('symbol', '_list'), ('string', '1\x002\x003'))
Before this patch, it will return ['1', '2', '3'], which are revision
numbers and causes unnecessary (expensive) partialmatch lookups.
This patch refacts gethashsymbols a bit, making sure the returning values
are always filtered.
test-drop.t
test-inhibit.t
test-simple4server.t
tests/test-simple4server-bundle2.t