[Lzip-bug] Specifying output for plzip

[Zach Lym]

I am having trouble specifying output for plzip:

➜  ~  ls -l
drwxrwxr-x  2 ubuntu ubuntu    4096 Dec 16 20:32 mirror
drwxr-xr-x 10 ubuntu ubuntu    4096 Dec 11 23:24 namecoin
-rwxr-xr-x  1 ubuntu ubuntu 4580000 Jun  1  2012 namecoind.old
-rwxr-xr-x  1 ubuntu ubuntu 1437538 Jun  1  2012 namecoind.old.lz

➜  ~  ls -l mirror
total 0

➜  ~  plzip --keep --output=mirror/headstart-2013-12-06 namecoind.old
plzip: Output file `namecoind.old.lz' already exists, skipping.

I have tried the following with the same result.
--output='mirror/headstart-2013-12-06'
--output=mirror/headstart-2013-12-06.lz
--output=./mirror/headstart-2013-12-06

I am using Ubuntu 12, instealled plzip from using Apt, and I am using
the Bash compatible zsh.  What am I missing?

Thank you,
-Zach Lym