dirstate: speed up read and write read: - single call to len(st) - fewer assignments for position tracking - don't split apart tuple from unpack - use a literal for the unpack spec write: - localize variables and functions - avoid copied function call - use % for string concatenation

adding a
adding b/a
a
b/a
644 a
644 b/a
b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3 644 a
b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3 644 b/a
a
a
b/a
a
b/a
% should fail
abort: unknown revision '2'!
abort: please specify just one revision
a
b/a