Change build URLs.

If url_pattern is set in zuul.conf, use it instead of the build
url supplied by jenkins when reporting a change to gerrit.

Change-Id: Ic66b1efb5c7eae0dbbfd1927ee2827d13729b568
Reviewed-on: https://review.openstack.org/11908
Reviewed-by: Clark Boylan <clark.boylan@gmail.com>
Approved: James E. Blair <corvus@inaugust.com>
Tested-by: Jenkins
diff --git a/tests/fixtures/zuul.conf b/tests/fixtures/zuul.conf
index 6df15c0..c031ae3 100644
--- a/tests/fixtures/zuul.conf
+++ b/tests/fixtures/zuul.conf
@@ -12,3 +12,4 @@
 layout_config=layout.yaml
 git_dir=/tmp/zuul-test/git
 push_change_refs=true
+url_pattern=http://logs.example.com/{change.number}/{change.patchset}/{pipeline.name}/{job.name}/{build.number}