DistutilsOptionError: must supply either home or prefix/exec-prefix -- not both
If you're using virtualenv*, it might be a good idea to double check which pip you're using.
If you see something like /usr/local/bin/pip you've broken out of your environment. Reactivating your virtualenv will fix this:
VirtualEnv: $ source bin/activate
VirtualFish: $ vf activate [environ]
*: I use virtualfish, but I assume this tip is relevant to both.
I've been usually installed python packages through pip.
For Google App Engine, I need to install packages to another target directory.
I've tried:

pip install -I flask-restful --target ./lib

but it fails with:

must supply either home or prefix/exec-prefix -- not both

How can I get this to work?