Pin pip version for the conflict tester & appveyor (#170)

Author: mr-c

appveyor.yml

@@ -22,7 +22,7 @@ environment:
 install:
   - "SET PATH=%PYTHON%;%PYTHON%\\Scripts;%PATH%"
   - "python --version"
-  - "pip install --disable-pip-version-check --user --upgrade pip"
+  - "pip install --disable-pip-version-check --user --upgrade pip==9.0.3"
   - "pip install --disable-pip-version-check --user --upgrade setuptools"
 
 build_script:

tox.ini

@@ -45,4 +45,6 @@ deps =
 [testenv:py27-pipconflictchecker]
 commands = pipconflictchecker
 whitelist_externals = pipconflictchecker
-deps = pip-conflict-checker
+deps =
+  pip-conflict-checker
+  pip==9.0.3