(note: this is a more clear version of a previously reported bug. sorry if this breaks bug-reporting etiquette, but the title was incredibly unclear)

### Please describe the problem.
In a v6 repository on a FAT filesystem, the view `/=*` replaces locally available files with placeholders normally used for unavailable files. 

### What steps will reproduce the problem?
[[!format sh """
[leo60228@digitaleo:~]$ fallocate -l $((1024*1024*1024*2)) demo.img

[leo60228@digitaleo:~]$ mkfs.vfat demo.img 
mkfs.fat 4.1 (2017-01-24)

[leo60228@digitaleo:~]$ mkdir demo

[leo60228@digitaleo:~]$ sudo mount -o loop,uid=${UID},gid=$(id -g $UID) demo.img demo

[leo60228@digitaleo:~]$ cd demo

[leo60228@digitaleo:~/demo]$ git init
Initialized empty Git repository in /home/leo60228/demo/.git/

[leo60228@digitaleo:~/demo]$ git commit --allow-empty -m 'init'
[master (root-commit) 8dc8e0a] init

[leo60228@digitaleo:~/demo]$ git annex init
init  
  Detected a filesystem without fifo support.

  Disabling ssh connection caching.

  Detected a crippled filesystem.

  Enabling direct mode.
ok
(recording state in git...)

[leo60228@digitaleo:~/demo]$ mkdir subdir

[leo60228@digitaleo:~/demo]$ echo hi > subdir/file

[leo60228@digitaleo:~/demo]$ git annex upgrade
upgrade (v5 to v6...) (scanning for unlocked files...)
ok
(recording state in git...)

[leo60228@digitaleo:~/demo]$ git annex add subdir/
add subdir/file ok
(recording state in git...)

[leo60228@digitaleo:~/demo]$ git commit -m 'add file'
[adjusted/master(unlocked) 0e870b3] add file
 1 file changed, 1 insertion(+)
 create mode 100644 subdir/file

[leo60228@digitaleo:~/demo]$ ls subdir/
file

[leo60228@digitaleo:~/demo]$ cat subdir/file 
hi

[leo60228@digitaleo:~/demo]$ git-annex view /=*
view (searching...) 
Switched to branch 'views/_=_'
ok

[leo60228@digitaleo:~/demo]$ ls subdir/
file_%subdir%

[leo60228@digitaleo:~/demo]$ cat subdir/file_%subdir% 
../.git/annex/objects/zQ/MQ/SHA256E-s3--98ea6e4f216f2fb4b69fff9b3a44842c38686ca685f3f55dc48c5d3fb1107be4/SHA256E-s3--98ea6e4f216f2fb4b69fff9b3a44842c38686ca685f3f55dc48c5d3fb1107be4
"""]]

### What version of git-annex are you using? On what operating system?
6.20180427 on NixOS. Installed via `nix-env -iA nixos.gitAndTools.git-annex`.

### Please provide any additional information below.
The repository is in v6 mode, because I was having strange issues with normal git commands such as `git commit` in direct mode. I know I needed to proxy the command, but are *all* git commands supposed to be broken in direct mode?

### Have you had any luck using git-annex before? (Sometimes we get tired of reading bug reports all day and a lil' positive end note does wonders)
Yep! I already use it to move files between my laptop's HDD and SSD, and to copy files between my many SD cards. I was trying this to see if I could not have to scroll as far on my 3D printer's menu.
