Permit bug numbers in rechecks.

But do not require them.
Also, retrigger the silent pipeline on rechecks.

Change-Id: I83d6ef44e0e37cb89204d02cd4e5b1fabc47cec9
Reviewed-on: https://review.openstack.org/18443
Reviewed-by: Clark Boylan <clark.boylan@gmail.com>
Approved: Jeremy Stanley <fungi@yuggoth.org>
Reviewed-by: Jeremy Stanley <fungi@yuggoth.org>
Tested-by: Jenkins

modules/openstack_project/files/zuul/layout.yaml

@@ -7,7 +7,7 @@ pipelines:
     trigger:
       - event: patchset-created
       - event: comment-added
-        comment_filter: (?i)^\s*recheck\.?\s*$
+        comment_filter: (?i)^\s*recheck( (?:bug|lp)[\s#:]*(\d+))?\s*$
     success:
       verified: 1
     failure:
@@ -20,7 +20,7 @@ pipelines:
         approval:
           - approved: 1
       - event: comment-added
-        comment_filter: (?i)^\s*reverify\.?\s*$
+        comment_filter: (?i)^\s*reverify( (?:bug|lp)[\s#:]*(\d+))?\s*$
     start:
       verified: 0
     success:
@@ -45,6 +45,7 @@ pipelines:
     manager: IndependentPipelineManager
     trigger:
       - event: patchset-created
+        comment_filter: (?i)^\s*recheck( (?:bug|lp)[\s#:]*(\d+))?\s*$
 
 
 jobs: