Revert "Get input files from relative path"
Revert "Get input files from relative path"

This reverts commit 08d863b2a272465f40e4445f737b8525d18f5e82.

This change is not general enough to work in different setups, such as
using a single virtual environment for the whole OSBS project installing
dependencies in development mode.

DBuildService/atomic-reactor,fr34k8/atomic-reactor,fr34k8/atomic-reactor,projectatomic/atomic-reactor,DBuildService/atomic-reactor,projectatomic/atomic-reactor