Log Message:
py-mercurial: update to 6.6.3.

= Mercurial 6.6.3 =

 * tests: don't use "status" operand of dd in test-censor.t (issue6858)
 * tests: make sha256line.py available for all tests
 * tests: use sha256line.py instead of /dev/random in test-censor.t (issue6858)
 * tests: fix nondeterministic test failure in test-contrib-perf.t
 * rust-changelog: don't panic on empty file lists
 * grep: restore usage of --include/--exclude options