Merge pull request #4553 from ThomasWaldmann/coverage-warning-1.1

get rid of confusing coverage warning, fixes #2069 (1.1-maint backport)

.coveragerc

@@ -1,5 +1,6 @@
 [run]
 branch = True
+disable_warnings = module-not-measured
 source = src/borg
 omit =
     */borg/__init__.py