### Please describe the problem.
Fails with below error

### What steps will reproduce the problem?
Click add another repository

Click Let's get start

Receive Error

### What version of git-annex are you using? On what operating system?
git-annex version 8.20200501
MacOS 10.15.4 (19E287)

### 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
[2020-05-07 15:01:42.693876] main: starting assistant version 8.20200501
(scanning...) [2020-05-07 15:01:42.754501] Watcher: Performing startup scan
(started...) 
07/May/2020:15:01:56 -0700 [Error#yesod-core] Failed to enable tor

enable-tor 
  You will be prompted for root's password
su: illegal option -- c
usage: su [-] [-flm] [login [args]]

git-annex: Failed to run as root: /usr/local/Cellar/git-annex/8.20200501/bin/git-annex enable-tor 501
failed
git-annex: enable-tor: 1 failed
 @(yesod-core-1.6.18-Chd8Br2Wdd9GRfQbrxaPhy:Yesod.Core.Class.Yesod src/Yesod/Core/Class/Yesod.hs:688:5)
07/May/2020:15:04:58 -0700 [Error#yesod-core] Failed to enable tor

enable-tor 
  You will be prompted for root's password
su: illegal option -- c
usage: su [-] [-flm] [login [args]]

git-annex: Failed to run as root: /usr/local/Cellar/git-annex/8.20200501/bin/git-annex enable-tor 501
failed
git-annex: enable-tor: 1 failed
 @(yesod-core-1.6.18-Chd8Br2Wdd9GRfQbrxaPhy:Yesod.Core.Class.Yesod src/Yesod/Core/Class/Yesod.hs:688:5)


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

### 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)

git-annex is working well syncing with my rsync.net account
