Hi Joey,


### Please describe the problem.
`git annex fromkey` on Windows fails with `git-annex: System.PosixCompat.Files.createSymbolicLink: not supported: illegal operation`

I guess it should create a unlocked file instead on Windows.

### What steps will reproduce the problem?

    mkdir test
    cd test
    git init
    git annex init test
    touch file
    git annex add file
    git annex sync
    git annex fromkey SHA256E-s0--e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855 file2

### What version of git-annex are you using? On what operating system?
git version 2.31.1.windows.1 <br>
git annex 8.20210331-g1fb59a63a <br>
Windows 10 Pro 1903 <br>

### 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)
Yes! git-annex is really great and there is nothing else like it. 

> [[fixed|done]] by making it create an unlocked file when used on an
> unlocked adjusted branch. --[[Joey]]
