Handle secondary rate limits that show up as "plain exceptions"

We previously handled secondary rate limit errors, however, it turns
out that we aren't getting the exception type that we were seeing then
for all secondary rate limits.

This PR updates to handle the generic "GitHubException" that PyGitHub
uses. If we get the more generic error and it contains a secondary
rate limit message from GitHub, we will handle with our usual "wait
and try again" strategy.

entrypoint.py

@@ -12,6 +12,7 @@
 from git.exc import GitCommandError
 from github import Github
 from github.GithubException import RateLimitExceededException
+from github.GithubException import GithubException
 
 CHANGELOG_LABELS = ['changelog - added',
                     'changelog - changed',
@@ -67,6 +68,20 @@
         else:
             print(ERROR + "Search failed again. Giving up." + ENDC)
             raise
+    except GithubException as e:
+        if "You have exceeded a secondary rate limit" in e.data['message']:
+            search_failures += 1
+            if search_failures <= 5:
+                print(NOTICE
+                    + "Search failed due to secondary rate limit exceeded. "
+                    + "Sleeping and trying again."
+                    + ENDC)
+                time.sleep(30)
+            else:
+                print(ERROR + "Search failed again. Giving up." + ENDC)
+                raise
+        else:
+            raise
 
 repo = github.get_repo(repo_name)
 pull_request = repo.get_pull(pr_id)