### Please describe the problem.

just want to check if that is "by design"... --force was demanded seem operation is dangerous, but I expected that it would still report success false if key was not actually dropped, at least if a key is a completely wrong key

so is that "by design" and I shouldn't care to check success field...?

### What version of git-annex are you using? On what operating system?
6.20160425+gitgffe2ea2-1~ndall+1

### Please provide any additional information below.

[[!format sh """

$> echo MD5E-s11--74d80f7d99b835e5189948c8d4297efd | git annex dropkey --batch --json --force
{"command":"dropkey","key":"MD5E-s11--74d80f7d99b835e5189948c8d4297efd","success":true}

$> ls -l
total 0
0 lrwxrwxrwx 1 yoh yoh 110 Apr 29 09:21 124 -> .git/annex/objects/MV/Jw/MD5E-s11--74d80f7d99b835e5189948c8d4297efd/MD5E-s11--74d80f7d99b835e5189948c8d4297efd

$> echo MD5E-s11--74d80f7d99b835e5189948c8d4297efd | git annex dropkey --batch --json --force
{"command":"dropkey","key":"MD5E-s11--74d80f7d99b835e5189948c8d4297efd","success":true}

$> echo MD5E-s11--74d80f7dsd99b835e5189948c8d4297efd | git annex dropkey --batch --json --force 
{"command":"dropkey","key":"MD5E-s11--74d80f7dsd99b835e5189948c8d4297efd","success":true}

$> echo MD5E-s11--74d80f7dsd99b835e5189948c8d4297efdsdfsdf | git annex dropkey --batch --json --force 
{"command":"dropkey","key":"MD5E-s11--74d80f7dsd99b835e5189948c8d4297efdsdfsdf","success":true}


"""]]

[[!meta author=yoh]]
[[!tag projects/datalad]]

> [[notabug|done]] --[[Joey]]
