--log-file ignored in gnupg master?

[Abel Luck]

The following command doesn't do what I expect it to do:

   gpg2 --debug-level expert --log-file ./debug.log --homedir . --list-keys

I expect gpg2 to spit all the data I'm getting on stdout into
./debug.log, but gpg2 isn't even creating the file, let alone writing to it.

Are my expectations misplaced or is something broken?

Using:
gpg (GnuPG) 2.1.0-beta129
libgcrypt 1.6.0-git2c54c4d

built from gnupg 19994466449a93704d38d429ca1ea36f63da0bf0

~abel