### Please describe the problem.

#### git annex unused fails with the message:

...
   86731   SHA256E-s13243--a6c5fe9710975e0b0ca01ec0b7eca6068a01b1b1c06adbd8ad7921e26d3b076d.h

   86732   SHA256E-s12872--f50b73d313a116ea21649d684f601840dbc8ed3c264165dd77fa5d54a1c57464.c

   86733   SHA256E-s6557264--6b502d56378b9919fd3c54c3bb2dc2906a326be8e9d477a8f3518419929f4706.dll

   86734   SHA256E-s141--c6227fe715dab2b4447b6e43af2b170ac66d82043aa81a14013c56be922e11db.out

   86735   SHA256E-s6564--ec4bcd833d071fff7d8cc81b908558acdeae2c9ba62f7d65b584effe6b36a8c6.c

git-annex: /bluepool/data/.git/annex/unused32594.tmp: commitBuffer: invalid argument (invalid character)
failed

git-annex: unused: 1 failed

#### A subsequent git annex dropunused does not work (there are 86735 files unused). A simple:
"git annex dropunused 1-10" produces:

git-annex: 1 not valid (run git annex unused for list)

#### It seems that the list of unused files was not saved (committed)

### What steps will reproduce the problem?

I suspect it can be reproduced by having files with non-english characters. 
This should be the sequence of commands to reproduce if one knew the invalid character:

git init .

git annex init .

touch "Invalid character in file name"

git annex add "Invalid character in file name"

git commit

git rm "Invalid character in file name"

git commit

git unused

However, I usually have "git annex watch" running so this might also have an influence on how (maybe not-escaped) filenames are added.

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

git annex standalone:

git-annex version: 5.20140306-g6e2e021

build flags: Assistant Webapp Pairing Testsuite S3 WebDAV Inotify DBus XMPP Feeds Quvi TDFA CryptoHash

key/value backends: SHA256E SHA1E SHA512E SHA224E SHA384E SKEIN256E SKEIN512E SHA256 SHA1 SHA512 SHA224 SHA384 SKEIN256 SKEIN512 WORM URL

remote types: git gcrypt S3 bup directory rsync web webdav tahoe glacier hook external

local repository version: 5

supported repository version: 5

upgrade supported from repository versions: 0 1 2 4



Ubuntu Raring: Linux i3 3.11.4-031104-generic


### Please provide any additional information below.

I guess I could provide the full output of git annex unused but I would rather not put it into this bug report for privacy reasons.

[[!format sh """
# If you can, paste a complete transcript of the problem occurring here.
# If the problem is with the git-annex assistant, paste in .git/annex/daemon.log


# End of transcript or log.
"""]]

> [[closing|done]], would still be nice to have verification my fix worked.
> --[[Joey]]