### Please describe the problem.
I keep getting the warning about ssh caching being disabled, even when I explicitly enable it.

### What steps will reproduce the problem?
See log below

### What version of git-annex are you using? On what operating system?
7.20200204 on Amazon Linux 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

(just-git-annex-env) 13:00  [viral-ngs-benchmarks] $ git annex sync -c annex.sshcaching=true
On branch is-devel
Your branch is up to date with 'origin/is-devel'.


It took 8.50 seconds to enumerate untracked files. 'status -uno'
may speed it up, but you have to be careful not to forget to add
new files yourself (see 'git help status').
nothing to commit, working tree clean
commit ok
pull origin
  You have enabled concurrency, but ssh connection caching is not enabled. This may result in multiple ssh processes prompting for pas\
swords at the same time.
ok

(just-git-annex-env) 13:00  [viral-ngs-benchmarks] $ uname -a
Linux ip-172-31-86-201.ec2.internal 4.14.165-131.185.amzn2.x86_64 #1 SMP Wed Jan 15 14:19:56 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
(just-git-annex-env) 13:02  [viral-ngs-benchmarks] $ git annex version
git-annex version: 7.20200204-g4db801d
build flags: Assistant Webapp Pairing S3 WebDAV Inotify DBus DesktopNotify TorrentParser MagicMime Feeds Testsuite
dependency versions: aws-0.21.1 bloomfilter-2.0.1.0 cryptonite-0.25 DAV-1.3.3 feed-1.0.1.0 ghc-8.6.5 http-client-0.5.14 persistent-sql\
ite-2.9.3 torrent-10000.1.1 uuid-1.3.13 yesod-1.6.0
key/value backends: SHA256E SHA256 SHA512E SHA512 SHA224E SHA224 SHA384E SHA384 SHA3_256E SHA3_256 SHA3_512E SHA3_512 SHA3_224E SHA3_2\
24 SHA3_384E SHA3_384 SKEIN256E SKEIN256 SKEIN512E SKEIN512 BLAKE2B256E BLAKE2B256 BLAKE2B512E BLAKE2B512 BLAKE2B160E BLAKE2B160 BLAKE\
2B224E BLAKE2B224 BLAKE2B384E BLAKE2B384 BLAKE2BP512E BLAKE2BP512 BLAKE2S256E BLAKE2S256 BLAKE2S160E BLAKE2S160 BLAKE2S224E BLAKE2S224\
 BLAKE2SP256E BLAKE2SP256 BLAKE2SP224E BLAKE2SP224 SHA1E SHA1 MD5E MD5 WORM URL
remote types: git gcrypt p2p S3 bup directory rsync web bittorrent webdav adb tahoe glacier ddar git-lfs hook external
operating system: linux x86_64
supported repository versions: 7
upgrade supported from repository versions: 0 1 2 3 4 5 6
local repository version: 7



# 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)

I've been using git-annex for 1.5 years to manage bioinformatics analyses.  It's a very versatile and well-designed tool.  I've been able to adapt it to many use cases;
the ability to easily write your own external backends has been especially helpful for that.  The amount of work and thought that has gone into designing/building git-annex is
enormous, and very much appreciated.

> [[done]]; see comment --[[Joey]]
