Tests: tune codecov comments

While the reason for the double comments by codecov is still unclear to me this change should disable the comments altogether if the coverage is not affected by this PR.

.codecov.yml

@@ -5,14 +5,17 @@ codecov:
 coverage:
   status:
     project: off
-    patch: on
+    patch:
+      default:
+        threshold: 0.01
 
 comment:
   layout: "diff, files"
   behavior: default
-  require_changes: false  # if true: only post the comment if coverage changes
+  require_changes: yes    # if true: only post the comment if coverage changes
   require_base: no        # [yes :: must have a base report to post]
   require_head: yes       # [yes :: must have a head report to post]
+  branch: master
 
 flags:
   # filter the folder(s) you wish to measure by that flag