Add missing Version.external_version_name (#10529)

* Add missing Version.external_version_name

This was implemented on Build, but not Version. Version does have an
opinionated version of this, but the output is "#4 (PR)" and I would
like "Pull request" instead.

* Formatting

Author: agjohnson

README.rst

@@ -38,7 +38,7 @@ Contributing
 
 You can find information about contributing to Read the Docs at our `Contribution page <https://docs.readthedocs.io/en/latest/contribute.html>`_.
 
-Quickstart for GitHub-Hosted Projects
+Quickstart for GitHub hosted projects
 -------------------------------------
 
 By the end of this quickstart, you will have a new project automatically updated

readthedocs/builds/models.py

@@ -274,6 +274,10 @@ def explicit_name(self):
         abbrev = "".join(word[0].upper() for word in external_origin.split())
         return template.format(name=self.verbose_name, abbrev=abbrev)
 
+    @property
+    def external_version_name(self):
+        return external_version_name(self)
+
     @property
     def ref(self):
         if self.slug == STABLE:
@@ -352,6 +356,7 @@ def commit_name(self):
 
         # By now we must have handled all special versions.
         if self.slug in NON_REPOSITORY_VERSIONS:
+            # pylint: disable=broad-exception-raised
             raise Exception('All special versions must be handled by now.')
 
         if self.type in (BRANCH, TAG):
@@ -407,7 +412,7 @@ def get_absolute_url(self):
             external=external,
         )
 
-    def delete(self, *args, **kwargs):  # pylint: disable=arguments-differ
+    def delete(self, *args, **kwargs):
         from readthedocs.projects.tasks.utils import clean_project_resources
         log.info('Removing files for version.', version_slug=self.slug)
         clean_project_resources(self.project, self)
@@ -699,7 +704,7 @@ def __init__(self, *args, **kwargs):
 
         super().__init__(*args, **valid_attributes)
 
-    def save(self, *args, **kwargs):  # pylint: disable=arguments-differ
+    def save(self, *args, **kwargs):
         return 0
 
 
@@ -1378,7 +1383,7 @@ def move(self, steps):
         self.save()
         return True
 
-    def delete(self, *args, **kwargs):  # pylint: disable=arguments-differ
+    def delete(self, *args, **kwargs):
         """Override method to update the other priorities after delete."""
         current_priority = self.priority
         project = self.project