I've been doing research about externals and have come to the conclusion that it is a best practice when using svn:externals to specify the externals at a particular revision, e.g.:

https://url/to/external@12345 name_of_external

I recently switched to doing this in my projects, and I have to agree that it is a lot safer to do. However, now I'm finding that this causes a failure in Subclipse's "merging best practices" pre-check because the externals are a different revision than the rest of the project checkout. I don't think this should be treated as a failure of the merging best practices when attempting to merge. I totally understand that a mixed-revision checkout is bad for merging, but in my opinion, externals set to a specific revision shouldn't count toward that check.

If it matters, the externals causing this problem are pointing to other locations inside of the same repository.