tweak codecov config.

.codecov.yml

@@ -1 +1,22 @@
+# validate this file:
+#   curl --data-binary @.codecov.yml https://codecov.io/validate
+
 comment: off
+
+# partial line support
+parsers:
+  javascript:
+    enable_partials: yes
+
+# docs:
+#   https://codecov.readme.io/v4.3.6/docs/commit-status
+#   https://gist.github.com/stevepeak/53bee7b2c326b24a9b4a
+coverage:
+  status:
+    project:
+      default:
+        threshold: 1%
+        if_not_found: success  # no commit found? still set a success
+    patch:
+      default:
+        if_not_found: success