merge weirdness item in WC not under revision control

Merging a branch back to trunk:

joey_at_dragon:~/src/mooix/mood>svn merge -r 1705:HEAD svn+ssh://svn.mooix.net/home/svn/mooix/branches/moox_embedding_rewrite_branch/mood
svn: Can't find an entry
svn: Can't merge changes into 'mood':it's not under revision control.

This threw me for a while, until I realized that in the WC directory was a
"mood" file (the binary produced during my last build), that was of
course not under revision control. I deleted it and the merge proceeded
as expected.

Is there some reason why subverson cared that I had a ./mood in the WC,
but did not care about mood.o, etc, that are also in the WC? Perhaps it
got confused since "mood" is also the name of the branch, and of the
directory I was doing the merge in.

Using subversion 0.26.0, still.

-- 
see shy jo