webdav: set the Lock-Token HTTP header when LOCKing existing files, not
just new files.

Section 10.5 says the Lock-Token applies when creating a new lock, not
just when (implicitly) creating a new file.

The litmus test expects this.

Change-Id: I8746154c9baba9a90b4e9db79cadb6839fc170c7
Reviewed-on: https://go-review.googlesource.com/3567
Reviewed-by: Dave Cheney <dave@cheney.net>
1 file changed