### Please describe the problem.

git-annex appears to not support relative paths for ssh remotes, e.g.:

`remote.example.com:path/to/git`

as opposed to:

`remote.example.com:/absolute/path/to/git`


### What steps will reproduce the problem?

I was following the steps to setup a [centralized git repo](https://git-annex.branchable.com/tips/centralized_git_repository_tutorial/on_your_own_server/).

I have setup an SSH remote (referred to below as `remote.example.com:path/to/git`) and pushed to it as described in the docs.  I then clone from this remote elsewhere:

```
0$ git clone remote.example.com:path/to/git remote
0$ cd remote
```

But `git-annex init` runs into the following problem:

```
0$ git annex init 'local'
init servo (scanning for unlocked files...)

  Unable to parse git config from origin

  Remote origin does not have git-annex installed; setting annex-ignore

  This could be a problem with the git-annex installation on the remote. Please make sure that git-annex-shell is available in PATH when you ssh into the remote. Once you have fixed the git-annex installation, run: git annex enableremote origin
ok
(recording state in git...)
0$
```

(Note problem but no non-zero return code.)

However, if I clone the remote with an absolute path there is no issue:

```shell
0$ git clone remote.example.com:/absolute/path/to/git remote
0$ cd remote
0$ git annex init 'local'
init servo (scanning for unlocked files...)
ok
(recording state in git...)
0$
```

I suspected something was amiss when things were taking a long time, and looking at the process tree showed ssh commands that include the string `/~/path/to/git`

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

```shell
0$ git-annex version
git-annex version: 8.20201127
build flags: Assistant Webapp Pairing Inotify DBus DesktopNotify TorrentParser MagicMime Feeds Testsuite S3 WebDAV
dependency versions: aws-0.22 bloomfilter-2.0.1.0 cryptonite-0.26 DAV-1.3.4 feed-1.3.0.1 ghc-8.8.4 http-client-0.6.4.1 persistent-sqlite-2.10.6.2 torrent-10000.1.1 uuid-1.3.13 yesod-1.6.1.0
key/value backends: SHA256E SHA256 SHA512E SHA512 SHA224E SHA224 SHA384E SHA384 SHA3_256E SHA3_256 SHA3_512E SHA3_512 SHA3_224E SHA3_224 SHA3_384E SHA3_384 SKEIN256E SKEIN256 SKEIN512E SKEIN512 BLAKE2B256E BLAKE2B256 BLAKE2B512E BLAKE2B512 BLAKE2B160E BLAKE2B160 BLAKE2B224E BLAKE2B224 BLAKE2B384E BLAKE2B384 BLAKE2BP512E BLAKE2BP512 BLAKE2S256E BLAKE2S256 BLAKE2S160E BLAKE2S160 BLAKE2S224E BLAKE2S224 BLAKE2SP256E BLAKE2SP256 BLAKE2SP224E BLAKE2SP224 SHA1E SHA1 MD5E MD5 WORM URL X*
remote types: git gcrypt p2p S3 bup directory rsync web bittorrent webdav adb tahoe glacier ddar git-lfs httpalso hook external
operating system: linux x86_64
supported repository versions: 8
upgrade supported from repository versions: 0 1 2 3 4 5 6 7
local repository version: 8
0$ cat /etc/issue
Debian GNU/Linux bullseye/sid \n \l

```


### 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


# 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)


> documentation fixed [[done]] --[[Joey]]
