We believe that your issue has been closed by the upload of
Version 0.3.35 of grml-etc-core from Michael Prokop <mika@grml.org>.
The explanation is attached below

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Format: 1.7
Date: Thu, 18 Oct 2007 10:22:36 +0200
Source: grml-etc-core
Binary: grml-etc-core
Architecture: source all
Version: 0.3.35
Distribution: unstable
Urgency: low
Maintainer: Michael Prokop <mika@grml.org>
Changed-By: Michael Prokop <mika@grml.org>
Description: 
 grml-etc-core - core ecetera files for the grml system
Changes: 
 grml-etc-core (0.3.35) unstable; urgency=low
 .
   * /etc/zsh/zshrc: support displaying version control information inside
     prompt (display on $RPROMPT). Just run 'VCS=1' to enable the feature.
     [Closes: issue305]
Files: 
 d9b18057ff2980630e1e85f7253564eb 596 grml optional grml-etc-core_0.3.35.dsc
 0621f4beef82387e1b2f962c9d134307 90343 grml optional grml-etc-core_0.3.35.tar.gz
 38d383fd12ae141c82d6b4118850977a 91834 grml optional grml-etc-core_0.3.35_all.deb

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Plus:
http://www.hiegel.fr/~hugues/Linux/Zsh/11_Prompts.zsh

Addon, also see:
http://dev.codemac.net/config.git?p=config.git;a=blob;f=zsh/
prompt;h=b0b1062db07da45c4a89bb7c719d831038cca645;hb=d53a4986652e406466ebc8cdd5a6cb7c2847bc71

See attached zsh configuration file of Carsten Hey to get an idea what I'm 
talking about. Should be made toggeable and I'd like to have support for 
mercurial as well.