Improve finding the right package when searching by source name
    
    Source name are of the type NEVR, ie: name-<epoch>-<version>-<release>,
    so to avoid finding foo1 when we are looking for foo, we've adjusted the
    logic to look for foo-, but this fails when there is a package such as
    foo-util.
    So with this commit, we ensure that the package returned is matching the
    pattern <name>-<digit>.
    
    Signed-off-by: Pierre-Yves Chibon <pingou@pingoured.fr>