new-version: run `fedpkg new-sources` on-demand
new-version: run `fedpkg new-sources` on-demand

`fedpkg new-sources` was run when `sources` file was present and not empty,
but such autodetection wasn't really working. This patch changes the default
behavior of `rdopkg new-version` to only run `fedpkg new-version` if
explicitly asked with new `-N/--new-sources` option.

Old `-n/--no-new-sources` is now default behavior and thus obsolete with no
effect except a warning.

Change-Id: I4468545febc7fcbdb50d0f8847e2984af6b48108

openstack-packages/rdopkg,openstack-packages/rdopkg,redhat-openstack/rdopkg,redhat-openstack/rdopkg