Allow using RSYNC_USERNAME env var

fwsreleasers/main.py

@@ -50,6 +50,10 @@ class RsyncSRPMSReleaser(RsyncReleaser):
 
         rsync = self.releaser_config.get(self.target, 'rsync').split(" ")
         for destination in rsync:
+            if RSYNC_USERNAME in os.environ:
+                print("%s set, using rsync username: %s" % (RSYNC_USERNAME,
+                        os.environ[RSYNC_USERNAME]))
+                destination = "%s@%s" % (os.environ[RSYNC_USERNAME], destination)
             for artifact in self.builder.artifacts:
                 if artifact.endswith('.src.rpm'):
                     cmd = "rsync %s %s %s" % (self.rsync_args, artifact, destination)