Comment # 1 on bug 1149131 from Thorsten Kukuk

transactional-update shell is for debugging, not installing software. If you
need to install non-RPM packages below /usr, then transactional-update is most
likely not the right choice for you.

Beside that: /etc is mounted in transactional-shell. Maybe you should describe
at first what your problem is and why pip install is failing?