zsh prompt garbled when launching screen from ssh command

zsh prompt garbled when launching screen from ssh command

When I ssh to a server with oh my zsh set-up and run screen directly from
the ssh command like this:
ssh -t -lbdb bdb-dev.myorg.com screen -R -x
the prompt is garbaged:
? ? bdb@bdb-dev:~/big_data_broker/ui [ve-bdb] git:?master? ?
? ?
If I ssh to the same server, then launch screen from there:
~ ⮀ ssh -lbdb -t bdb-dev
Last login: Wed Aug 21 12:50:49 2013 from 10.x.x.x
╭ ➜ bdb@bdb-dev:~ [ve-bdb]
╰ ➤ screen -R -x
then the prompt is ok:
╭ ➜ bdb@bdb-dev:~/big_data_broker/ui [ve-bdb] git:&lsqauo;master›
✗
╰ ➤
I have dumped environment variables in both cases to a file and diffed:
they are the same.
my .screenrc on the server is:
autodetach on # Autodetach session on hangup instead of terminating screen
completely
startup_message off # Turn off the splash screen
defscrollback 30000 # Use a 30000-line scrollback buffer
vbell off
hardstatus alwayslastline
hardstatus string '%{= kG}[ %{G}%H %{g}][%= %{=
kw}%?%-Lw%?%{r}(%{W}%n*%f%t%?(%u)%?%{r})%{w}%?%+Lw%?%?%= %{g}][%{B} %d/%m
%{W}%c %{g}]'
term xterm
# Make xterm scrolling work properly with screen.
termcapinfo xterm-256color|xterm-color|xterm|xterms|xs|rxvt ti@:te@
Using iTerm2 Build 1.0.0.20130624 on OSX 10.8.4, virtualenvwrapper and the
'seeker' oh-my-zh theme.
Why is the prompt garbaged in the first case and how to fix it?