### Please describe the problem.


### What steps will reproduce the problem?

Run with a custom external remote which provides CHECKURL-CONTENTS response with filename, and then run 
annex addurl --file=existing_file URL   expecting to get that URL assigned to existing_file

Alternatively,  there is a small test repo
<http://www.onerussian.com/tmp/tmpSqa8CH.tgz>
with  .git/bin/git-annex-remote-dl+archive under /tmp/tmpSqa8CH having what was supposed to be a replayable protocol (if you do 

     cd /tmp/tmplVoa6C; PATH=/tmp/tmplVoa6C/.git/bin:$PATH git annex --debug addurl --file test2.dat --relaxed dl+archive:SHA256E-s163--e424b6fef10c18b9aaa5bc773ef62a2632eaf1448ff3372d43557be4adca6419.tar.gz/a/d/test.dat

But for this one,  I guess since addurl command actually succeeds, it is no longer replayable (protocol of interactions diverges) but you will see all the interactions between my remote and annex in that file recorded for you.  And you will see the test.dat uncommitted and with somewhat obscured URL-based key, although originally the call was

     git annex --debug addurl --file test2.dat --relaxed dl+archive:SHA256E-s163--1f86ca26e1ca3cad3e8c8f1684d558b5e5f48d5928e0db45ab2e7d3be3d35307.tar.gz/a/d/test.dat

from which I expected test2.dat get a new URL and that Filename remote spit out being ignored

### What version of git-annex are you using? On what operating system?

5.20150327+git27-g6af24b6-1

> [[fixed|done]] --[[Joey]]
