Fixed error message.

Author: Paul-Ferrell

stackinator/mirror.py

@@ -84,7 +84,7 @@ def _load_mirrors(self, cmdline_cache: Optional[str]) -> Dict[str, Dict]:
             mirrors['legacy_cache_cfg'] = legacy_cache
 
 
-        caches = [mirror for mirror in mirrors.values() if mirror['cache']]
+        caches = {name: mirror for name, mirror in mirrors.items() if mirror['cache']]
         if len(caches) > 1:
             raise MirrorError(
                 "Mirror config has more than one mirror specified as the build cache destination.\n"

unittests/data/systems/mirror-basic/mirrors.yaml

@@ -0,0 +1,8 @@
+fake-mirror:
+  url: https://google.com
+disabled-mirror:
+  url: https://google.com
+  enabled: false
+bootstrap-mirror:
+  url: https://mirror.spack.io
+  bootstrap: true

unittests/test_mirrors.py

@@ -35,9 +35,9 @@ def test_mirror_init(systems_path, valid_mirrors):
 def test_command_line_cache(systems_path):
     """Check that adding a cache from the command line works."""
 
-    mirrors = mirror.Mirrors(systems_path/'mirror-ok', cmdline_cache=systems_path.as_posix())
+    mirrors = mirror.Mirrors(systems_path/'mirror-basic', cmdline_cache=systems_path.as_posix())
 
-    assert len(mirrors.mirrors) == 4
+    assert len(mirrors.mirrors) == 3
 
 
 def test_create_spack_mirrors_yaml(systems_path):