Use DummyYaqlYamlLoader to load classes during upload

This commit changes the loader, that loads MuranoPL classes during
package upload to DummyYaqlYamlLoader. This would allow importing and parsing
packages that contain '!yaql' tag without any errors, when importing to
glare.

Change-Id: I9071bb479019cac20bf61f110154082063c9d777
Closes-Bug: #1586028

muranoclient/common/utils.py

@@ -354,7 +354,8 @@ class Package(FileWrapperMixin):
                 filename = "Classes/%s" % class_file
                 if filename not in self.contents.namelist():
                     continue
-                klass = yaml.safe_load(self.contents.open(filename))
+                klass = yaml.load(self.contents.open(filename),
+                                  DummyYaqlYamlLoader)
                 self._classes[class_name] = klass
         return self._classes
 
@@ -587,6 +588,14 @@ class Bundle(FileWrapperMixin):
             yield pkg_obj
 
 
+class DummyYaqlYamlLoader(yaml.SafeLoader):
+    """Constructor that treats !yaql as string."""
+    pass
+
+DummyYaqlYamlLoader.add_constructor(
+    u'!yaql', DummyYaqlYamlLoader.yaml_constructors[u'tag:yaml.org,2002:str'])
+
+
 class YaqlYamlLoader(yaml.SafeLoader):
     pass
 

releasenotes/notes/yamlloader-glare-d7d0506f6711b650.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - It is now possible to import packages with '!yaql' tag, when glare
+    is used as backend. Before this fix, importing such package caused
+    a parsing error.