Close connection prior to falling back to get, since we change the url back to the original at that time.

linkcheck/checker/httpurl.py

@@ -283,6 +283,8 @@ class HttpUrl (internpaturl.InternPatternUrl, proxysupport.ProxySupport, pooledc
 
     def fallback_to_get(self):
         """Set method to GET and clear aliases."""
+        self.close_response()
+        self.close_connection()
         self.method = "GET"
         self.aliases = []
         self.urlparts = strformat.url_unicode_split(self.url)