tests/testlib/obsmarker-common.sh

rust-status: use bare hg status fastpath from Python

This change also adds a test case for subrepos.
Repeating the benchmark information from the `hg-core` commit:

On the Netbeans repository:
C: 840ms
Rust+C: 556ms

Mozilla Central with the one pattern that causes a fallback removed:
C: 2.315s
Rust+C: 1.700s

Differential Revision: https://phab.mercurial-scm.org/D7931

mkcommit() {
   name="$1"
   shift
   echo "$name" > "$name"
   hg add "$name"
   hg ci -m "$name" "$@"
}

getid() {
   hg log --hidden --template '{node}\n' --rev "$1"
}

cat >> $HGRCPATH <<EOF
[alias]
debugobsolete=debugobsolete -d '0 0'
EOF