rust-dirstate-v2: fix the unused bytes counter when rewriting the dirstate
As per the previous patch, the counter was incorrectly carried over from the
old docket when it should be reset for a complete rewrite.
Differential Revision: https://phab.mercurial-scm.org/D12594
# Rust builds with a modern MSVC and uses a newer CRT.
# Python 2.7 has a shared library dependency on an older CRT (msvcr90.dll).
# We statically link the modern CRT to avoid multiple msvcr*.dll libraries
# being loaded and Python possibly picking up symbols from the newer runtime
# (which would be loaded first).
[target.'cfg(target_os = "windows")']
rustflags = ["-Ctarget-feature=+crt-static"]