I did a quick test on my workstation ...

$ svn --version
svn, version 1.6.6 (r40053)
compiled Jun 5 2011, 14:51:47

$ svn co https://forge.abcd.harvard.edu/svn/plastimatch/plastimatch/trunk --non-interactive
svn: OPTIONS of 'https://forge.abcd.harvard.edu/svn/plastimatch/plastimatch/trunk': Server certificate verification failed: issuer is not trusted (https://forge.abcd.harvard.edu)

$ svn co https://forge.abcd.harvard.edu/svn/plastimatch/plastimatch/trunk --non-interactive --trust-server-cert
A trunk/LICENSE.TXT
A trunk/cmake
A trunk/cmake/FindZLIB.cmake
A trunk/cmake/FindRTK.cmake
[...]

The option "--trust-server-cert" is passed when an external project is configured with SVN_TRUST_CERT 1

Looking at the dashboard, the extension build as expected on the factory: http://slicer.cdash.org/buildSummary.php?buildid=46584

Is this still an issue ?

I never said that this switch doesn't get passed.
The problem is that until I enter the 'GNOME keyring' password it can't do a checkout or update.

These are my outputs:

perklab@csaba-VirtualBox:~/Devel/SlicerRT_D64-bin$ svn --version
svn, version 1.6.17 (r1128011)
compiled Dec 17 2011, 16:12:52

perklab@csaba-VirtualBox:~/Devel$ svn co https://forge.abcd.harvard.edu/svn/plastimatch/trunk --non-interactive
svn: OPTIONS of 'https://forge.abcd.harvard.edu/svn/plastimatch/trunk': authorization failed: Could not authenticate to server: rejected Basic challenge https://forge.abcd.harvard.edu)

perklab@csaba-VirtualBox:~/Devel$ svn co https://forge.abcd.harvard.edu/svn/plastimatch/trunk --non-interactive --trust-server-cert
svn: OPTIONS of 'https://forge.abcd.harvard.edu/svn/plastimatch/trunk': authorization failed: Could not authenticate to server: rejected Basic challenge https://forge.abcd.harvard.edu)

Without the non-interactive switch it says:
Password for '(null)' GNOME keyring:

May be you can disable gnome keyring on your dashboard ?
Which version of linux are you using ?

I use Ubuntu 12.04 64bit.

I'll try to disable that.
It was a long time since I worked on Linux, I didn't know I can disable it.

Thanks!

I think I managed to fix it.
I'll let the nightly and continuous builds run a bit and then close this issue if everything's OK.
Thanks for the help!

Closing the issue based on Csaba comments. Csaba will close the issue accordingly.