Description of problem:
When issuing `rhpkg new-sources tarball.tar.gz --path differentdir/`, rhpkg check if both `differentdir/tarball.tar.gz` and `tarball.tar.gz` exist. If either of these checks fail, rhpkg reports "No such file or directory".

So basically rhpkg expects the tarball to be on two places at the same time.

Version-Release number of selected component (if applicable):
Version     : 1.26
Release     : 1.fc22

How reproducible:
Always

Steps to Reproduce:
1. cd $HOME
2. rhpkg clone somerepo;
3. touch tarball.tar.gz
4. rhpkg --path somerepo/ new-sources tarball.tar.gz

Actual results:
Could not execute new_sources: Path does not exist or is not a file: tarball.tar.gz
-or-
Could not execute new_sources: [Errno 2] No such file or directory: 'tarball.tar.gz'

Expected results:
Successful upload

Additional info:
1st check is in `pyrpkg/cli.py`, new_sources function
2nd check is somewhere in `pyrpkg/__init__.py`, upload function

As a workaround, one may specify full path to the tarball. This produces the successful upload.