Merge pull request #48 from ganwell/t/test_mirror_update_fac1

test: convert test_mirror_update to new test

TODO

@@ -1,3 +1,5 @@
+# NEXT: Add coverage and mypy
+
 # Update old files
 
 The following files have just been copied without checking if their content is ok:
@@ -11,4 +13,10 @@ The reason for this is to ensure the continuity of the git history.
 # Tool to convert yaml config to toml
 
 - This is probably just a sub-command of pyaptly
-- We probably still want to switch to a modern yaml parser
+- We probably still want to switch to a modern yaml parser
+
+# Rename testsets mentioning google
+
+# Replace all subprocess commands with a modern one (usually run())
+
+# All logging should be done via logging (no stdout/stderr)