fix windows builds
Appveyor isn't able to replace the running executable. We'll run it
from inside the interpreter to fix build issues.
@@ -41,7 +41,7 @@ install:
# Upgrade to the latest version of pip to avoid it displaying warnings
# about it being out of date.
- - "pip install --disable-pip-version-check --user --upgrade pip"
+ - "python -m pip install --upgrade pip wheel"
- "C:\\MinGW\\bin\\mingw32-make"
test_script:
