Fix concurrent builds of the same package
Fix concurrent builds of the same package

If we are running concurrent builds (workers=2 in projects.ini) and
we happen to build two commits for the same package at the same time,
the build_srpm.sh script will try to copy the generated tarball
twice to the same directory (source_git/dist), causing an issue.

This commit fixes this by copying the tarball to a unique directory
under $TOP_DIR.

Change-Id: I61de85510242e9bf9fbb2084a8ebe7a88dc52417

openstack-packages/DLRN,openstack-packages/DLRN,openstack-packages/delorean,openstack-packages/delorean