Append a '-' to the name provided when searching packages by their source name
    
    This way the LIKE query that is done will match <foo>- rather than all
    the packages starting with <foo> (which may results in foo1 being returned
    instead of foo).
    
    Fixes https://pagure.io/mdapi/issue/96
    
    Signed-off-by: Pierre-Yves Chibon <pingou@pingoured.fr>