run-tests: fix broken regular expression
The regular expression in use passed tests because the test repo only
has single-digit changesets present. When I tried to use this for real
today, it broke, because the regular expression would only match a
single digit.
https://xkcd.com/1171/, or something like that.
# This config file points Mercurial at the system-wide certificate
# store from the ca-certificates package.
[web]
cacerts = /etc/ssl/certs/ca-certificates.crt