On Gaming, we just had a strange situation where a question belonging on the meta was asked on the main site, so we closed it and migrated it to the meta. Then the OP deleted his question on the meta, so as per this change, the question was unlocked on the main site and had to be re-migrated.
Since different questions belong on a main site vs. on a meta, and since migrations like this are within a single community, it's more likely that a question migrated in this fashion would be closed for some valid reason but still belong more on the target site than on the original site. Therefore it doesn't really make sense to have migration rejection in this case.
The posts in question are http://gaming.stackexchange.com/posts/69573/revisions and http://meta.gaming.stackexchange.com/posts/4720/revisions.