tests: Use host repositories for make vm

to help with running the tests by hand on downstream snapshots.
In that scenario we want TEST_OS/VM_IMAGE to look as closely as
possibly like the snapshot that we'd like to test.

Cherry-picked from 1351c4dc63

Related: rhbz#1770193

Makefile

@@ -127,6 +127,15 @@ $(VM_IMAGE): srpm bots
 vm: $(VM_IMAGE)
 	echo $(VM_IMAGE)
 
+# grab all repositories from the host system, overwriting what's inside the VM
+# and update the image. Mostly used when testing downstream snapshots to make
+# sure VM_IMAGE is as close as possible to the host!
+vm-local-repos: vm
+	bots/image-customize -v \
+		--upload /etc/yum.repos.d:/etc/yum.repos.d/ \
+		--run-command "yum -y update" \
+		$(TEST_OS)
+
 vm-reset:
 	rm -f $(VM_IMAGE) $(VM_IMAGE).qcow2
 

test/README.md

@@ -38,6 +38,13 @@ To delete the generated image, run
 Base images are stored in `bots/images`. Set `TEST_DATA` to override this
 directory.
 
+Use
+
+    $ make vm-local-repos
+
+to configure the image with all repositories found on the host system! This
+is mostly useful when running tests by hand on a downstream snapshot!
+
 ## Running tests
 
 After building a test image, run