Fix around buildbot's inane WithProperties DSL again.

whitequark · whitequark · commit 3d0799542c6c · 2018-01-20T00:11:00.000Z
diff --git a/master.cfg b/master.cfg
@@ -134,7 +134,7 @@ def condaEnv(use_local=False, extra_vars={}):
 def addUpdateSteps(factory, project):
     defaultrepo = "https://github.com/m-labs/" + project
     factory.addStep(
-        Git(repourl           = WithProperties('%(repository:-{})s'.format(defaultrepo)),
+        Git(repourl           = WithProperties('%(repository:~{})s'.format(defaultrepo)),
             submodules        = True,
             mode              = 'incremental',
             progress          = True))
