### Please describe the problem.

Initializing a httpalso remote fails by requesting an encryption mode (but then rejecting it).

### What steps will reproduce the problem?

[[!format sh """
git init test1
cd test1
dd if=/dev/urandom count=1000 of=testfile
git annex init
git annex add testfile
git commit -m "initial checkin"
cd ..
git clone test1 test2
cd test2
git annex init
git annex initremote --sameas=origin origin-http type=httpalso url=http://example.com/foo
"""]]

That is the minimal example as I understand the [httpalso documentation](special_remotes/httpalso/).

This gives an error message:

```
initremote origin-http 
git-annex: Specify encryption=hybrid or encryption=none or encryption=pubkey or encryption=shared or encryption=sharedpubkey.
failed
git-annex: initremote: 1 failed
```

Adding `encryption=none` (or any other) gives `Unexpected parameters: encryption`.

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

git annex 8.20200908 on current Debian sid (as packaged)

### Have you had any luck using git-annex before?

My first git-annex repository dates back 2010-12-21 ... so: yes.

The introduction of httpalso simplifies the setup in the [annex-to-web](https://gitlab.com/chrysn/annex-to-web)  server, which on one hand consumes them in order to pass out redirects, and on the other hand .