Use re.match() to simplify Version.identifier_friendly

re_sha is only used once so the overhead of calling
re.compile() implicitly is minimal which means we
can simplify the code by using re.match() instead.

Author: berkerpeksag

readthedocs/builds/models.py

@@ -164,8 +164,7 @@ def delete(self, *args, **kwargs):
     @property
     def identifier_friendly(self):
         '''Return display friendly identifier'''
-        re_sha = re.compile(r'^[0-9a-f]{40}$', re.I)
-        if re_sha.match(self.identifier):
+        if re.match(r'^[0-9a-f]{40}$', self.identifier, re.I):
             return self.identifier[:8]
         return self.identifier