dirstate: simplify the ambiguity clearing at write time
The serialization function is already doing this, so we don't need to do it
manually. We just need to propagate the right definition of "now".
Differential Revision: https://phab.mercurial-scm.org/D11501
edition = "2018"
max_width = 79
wrap_comments = true
error_on_line_overflow = true