### Please describe the problem.

git-annex attempts to create files with question marks in them on my direct repository on a FAT32 drive.  This fails.

### What steps will reproduce the problem?

git annex addurl 'http://rf.proxycast.org/m/media/273073201426.mp3?c=culture&p=La+t%C3%AAte+au+carr%C3%A9_10212&l3=20131002&l4=&media_url=http%3A%2F%2Fmedia.radiofrance-podcast.net%2Fpodcast09%2F10212-02.10.2013-ITEMA_20531825-0.mp3'

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

[[!format sh """
$ cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=12.04
DISTRIB_CODENAME=precise
DISTRIB_DESCRIPTION="Ubuntu 12.04.3 LTS"

$ git annex version
git-annex version: 4.20130922-g7dc188a
build flags: Assistant Webapp Pairing Testsuite S3 WebDAV Inotify DBus XMPP Feeds Quvi
local repository version: 4
default repository version: 3
supported repository versions: 3 4
upgrade supported from repository versions: 0 1 2
"""]]

### Please provide any additional information below.

[[!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

$ git annex addurl 'http://rf.proxycast.org/m/media/273073201426.mp3?c=culture&p=La+t%C3%AAte+au+carr%C3%A9_10212&l3=20131002&l4=&media_url=http%3A%2F%2Fmedia.radiofrance-podcast.net%2Fpodcast09%2F10212-02.10.2013-ITEMA_20531825-0.mp3'
addurl rf.proxycast.org_m_media_273073201426.mp3_c=culture&p=La+t%C3%AAte+au+carr%C3%A9_10212&l3=20131002&l4=&media_url=http%3A%2F%2Fmedia.radiofrance-podcast.net%2Fpodcast09%2F10212-02.10.2013-ITEMA_20531825-0.mp3 (downloading http://rf.proxycast.org/m/media/273073201426.mp3?c=culture&p=La+t%C3%AAte+au+carr%C3%A9_10212&l3=20131002&l4=&media_url=http%3A%2F%2Fmedia.radiofrance-podcast.net%2Fpodcast09%2F10212-02.10.2013-ITEMA_20531825-0.mp3 ...)
/media/sixtyfour/audio/.git/annex/tmp/URL--http&c%%rf.proxycast.org%m%media%273073201426.mp3?c=culture&ap=La+t&sC3&sAAte+au+carr&sC3&sA9_10212&al3=20131002&al4=&amedia_url=http&s3A-86e83c2aaa925b3bc337c1d6a27bd300: Argument invalide

git-annex: /media/sixtyfour/audio/.git/annex/transfer/failed/download/00000000-0000-0000-0000-000000000001/URL--http&c%%rf.proxycast.org%m%media%273073201426.mp3?c=culture&ap=La+t&sC3&sAAte+au+carr&sC3&sA9_10212&al3=20131002&al4=&amedia_url=http&s3A-86e83c2aaa925b3bc337c1d6a27bd300: openFile: invalid argument (Invalid argument)
failed
git-annex: addurl: 1 failed

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

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