Appveyor should use the same version of pip as everything else

Author: nedbat

appveyor.yml

@@ -131,11 +131,9 @@ install:
   # Check that we have the expected version and architecture for Python
   - "python -c \"import struct, sys; print('{}\\n{}-bit'.format(sys.version, struct.calcsize('P') * 8))\""
 
-  # Upgrade to the latest version of pip to avoid it displaying warnings
+  # Upgrade to the right version of pip to avoid it displaying warnings
   # about it being out of date.
-  - "python -m pip install --disable-pip-version-check --upgrade pip"
-  # And upgrade virtualenv to get the latest pip inside .tox virtualenvs.
-  - "python -m pip install --disable-pip-version-check --upgrade virtualenv"
+  - "python -m pip install --disable-pip-version-check -r requirements/pip.pip"
 
   # Install requirements.
   - "%CMD_IN_ENV% pip install -r requirements/ci.pip"

requirements/dev.pip

@@ -4,8 +4,7 @@
 # Requirements for doing local development work on coverage.py.
 # https://requires.io/github/nedbat/coveragepy/requirements/
 
-pip==20.0.2
-virtualenv==16.7.9
+-r pip.pip
 
 pluggy==0.13.1
 

requirements/pip.pip

@@ -0,0 +1,5 @@
+# Licensed under the Apache License: http://www.apache.org/licenses/LICENSE-2.0
+# For details: https://github.com/nedbat/coveragepy/blob/master/NOTICE.txt
+
+pip==20.0.2
+virtualenv==16.7.9

tox.ini

@@ -14,8 +14,8 @@ extras =
 deps =
     # Check here for what might be out of date:
     #   https://requires.io/github/nedbat/coveragepy/requirements/
+    -r requirements/pip.pip
     -r requirements/pytest.pip
-    pip==20.0.2
     setuptools==41.4.0
     # gevent 1.3 causes a failure: https://github.com/nedbat/coveragepy/issues/663
     py{27,35,36}: gevent==1.2.2