Twisted apparently not supporting 3.7 on Windows yet.

Author: Julian

.appveyor.yml

@@ -26,12 +26,13 @@ environment:
 
     - TOXENV: py36-tests
       PYTHON: "C:\\Python36-x64"
-
-    - TOXENV: py37-tests
-      PYTHON: "C:\\Python37"
-
-    - TOXENV: py37-tests
-      PYTHON: "C:\\Python37-x64"
+    # Twisted currently failing to install.
+    #
+    # - TOXENV: py37-tests
+    #   PYTHON: "C:\\Python37"
+    #
+    # - TOXENV: py37-tests
+    #   PYTHON: "C:\\Python37-x64"
 
 init:
   - echo "TOXENV - %TOXENV%"