run-tests: use regex when searching for $HGPORT in test output
This prevents spurious errors when a changeset hash happens to match
the port number. Before, this invocation gave a test failure:
$ ./run-tests.py test-log.t --port 24427
ERROR: /home/mg/src/mercurial-crew/tests/test-log.t output changed
--- /home/mg/src/mercurial-crew/tests/test-log.t
+++ /home/mg/src/mercurial-crew/tests/test-log.t.err
@@ -626,12 +626,12 @@
$ hg log -b default
changeset: 2:
c3a4f03cc9a7
- parent: 0:
24427303d56f
+ parent: 0:$HGPORT303d56f
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: commit on default
...