revlog.py: always return tuples from parents and parentrevs
There's at least one place doing parentrevs(rev) != (rev-1, -1),
which is always true with revlog v0, since parentrevs returns a list
in this case.
--
A dir/b.o
? a.c
? a.o
? dir/c.o
? syntax
--
abort: .hgignore: invalid pattern (relre): *.o
--
A dir/b.o
? .hgignore
? a.c
? syntax
--
.hgignore: ignoring invalid syntax 'invalid'
A dir/b.o
? .hgignore
? a.c
? a.o
? dir/c.o
? syntax
--
A dir/b.o
? .hgignore
? a.c
? syntax
--
A dir/b.o
? .hgignore
? a.c
? a.o
? dir/c.o
--
A dir/b.o
--
A b.o