Fix failure with unpacking tarball
    
    Executing(%prep): /bin/sh -e /var/tmp/rpm-tmp.JbtjGM
    + umask 022
    + cd /builddir/build/BUILD
    + cd /builddir/build/BUILD
    + rm -rf python-dockerfile-parse-2.0.1
    + /usr/lib/rpm/rpmuncompress -x /builddir/build/SOURCES/2.0.1.tar.gz
    + STATUS=0
    + '[' 0 -ne 0 ']'
    + cd python-dockerfile-parse-2.0.1
    /var/tmp/rpm-tmp.JbtjGM: line 40: cd: python-dockerfile-parse-2.0.1: No such file or directory