when importing via alias, make sure the alias gets added to sys.modules

so that when a future item imports by the alias, it gets the same module
instead of rerunning the module/code again..

casimport/__init__.py

@@ -310,6 +310,7 @@ class CASFinder(MetaPathFinder, Loader):
 
 	# MetaPathFinder methods
 	def find_spec(self, fullname, path, target=None):
+		aliases_to_add = ()
 		if path is None:
 			ms = ModuleSpec(fullname, self, is_package=True)
 		else:
@@ -335,10 +336,11 @@ class CASFinder(MetaPathFinder, Loader):
 					raise ValueError('unable to find base hash url for alias %s' % repr(arg))
 
 				# fix up the full name:
+				aliases_to_add = (fullname,)
 				fullname = 'cas.v1_f_%s' % hashurl.path[1:]
 
 			ms = ModuleSpec(fullname, self, is_package=False,
-			    loader_state=(hashurl,))
+			    loader_state=(hashurl,) + aliases_to_add)
 
 		return ms
 
@@ -348,34 +350,38 @@ class CASFinder(MetaPathFinder, Loader):
 	# Loader methods
 	def exec_module(self, module):
 		if module.__name__ == 'cas':
-			pass
+			return
+
+		(url, *aliases) = module.__spec__.loader_state
+		for load in self._loaders:
+			try:
+				data = load.fetch_data(url)
+				break
+			except Exception:
+				pass
+
 		else:
-			(url,) = module.__spec__.loader_state
-			for load in self._loaders:
-				try:
-					data = load.fetch_data(url)
-					break
-				except Exception:
-					pass
+			for url in self._aliases[
+			    self._makebasichashurl(url)]:
+				url = urllib.parse.urlparse(url)
+				for load in self._loaders:
+					try:
+						data = load.fetch_data(url)
+						break
+					except Exception:
+						pass
+				else:
+					continue
 
+				break
 			else:
-				for url in self._aliases[
-				    self._makebasichashurl(url)]:
-					url = urllib.parse.urlparse(url)
-					for load in self._loaders:
-						try:
-							data = load.fetch_data(url)
-							break
-						except Exception:
-							pass
-					else:
-						continue
+				raise ValueError('unable to find loader for url %s' % repr(urllib.parse.urlunparse(url)))
 
-					break
-				else:
-					raise ValueError('unable to find loader for url %s' % repr(urllib.parse.urlunparse(url)))
+		exec(data, module.__dict__)
 
-			exec(data, module.__dict__)
+		# we were successful, add the aliases
+		for i in aliases:
+			sys.modules[i] = module
 
 _supportedmodules = {
 	'https': HTTPSCAS.fromconfig,
@@ -641,6 +647,18 @@ class Test(unittest.TestCase):
 			# they are the same
 			self.assertIs(hello_alias, hello_hash)
 
+			# that when we reimport the alias
+			from cas.v1_a_hello import hello as hello_alias
+
+			# it is still the same
+			self.assertIs(hello_alias, hello_hash)
+
+			# and when we reimport the hash
+			from cas.v1_f_330884aa2febb5e19fb7194ec6a69ed11dd3d77122f1a5175ee93e73cf0161c3 import hello as hello_hash
+
+			# it is still the same
+			self.assertIs(hello_alias, hello_hash)
+
 	def test_aliasimports(self):
 		# setup the cache
 		cachedir = self.tempdir / 'cache'