The mirror application launch config from the cvs is setup to handle repositories, but not update sites. If you add the org.eclipse.equinox.p2.updatesite bundle (and the required bundles of updatesite) to your launch configuration then you should be able to mirror updatesites.

OK. Before adding the org.eclipse.equinox.p2.updatesite bundle to the P2 agent download (alongside the p2.tools bundle in the p2.agent dropins folder) I tried rerunning the pydev mirror. This time it worked. When I tried last week it failed repeatedly. I tried other sites that has also failed. These mirrored too. (The MirrorApplication even seemed to successfully merge features from different external sites into the same mirror.) So who knows what was up last week. (And it seems that the p2.updatesite bundle is not required after all.)

However, I then tried selecting the IUs I wanted from a particular site using the -ius argument. The resulting mirror contained only the following: a plugins directory, an artifacts.xml and a content.xml. It was not browsable the P2 install manager. Is this a bug?

Here is the output of the application:

[::p2-wrapper-script::] Mirroring http://www.perforce.com/downloads/http/p4-wsad/install/ to C:/dev/workshop/eclipseide/3.4/mirrors/3rdparty
    [mkdir] Created dir: C:\dev\workshop\eclipseide\3.4\mirrors\3rdparty
       [P2] Install location:
       [P2]     file:/c:/dev/workshop/eclipseide/3.4/tools/equinox-p2-agent-3.4-win32/
       [P2] Configuration file:
       [P2]     file:/c:/dev/workshop/eclipseide/3.4/tools/equinox-p2-agent-3.4-win32/configuration/config.ini loaded
       [P2] Configuration location:
       [P2]     file:/c:/dev/workshop/eclipseide/3.4/tools/equinox-p2-agent-3.4-win32/configuration/
       [P2] Framework located:
       [P2]     file:/c:/dev/workshop/eclipseide/3.4/tools/equinox-p2-agent-3.4-win32/plugins/org.eclipse.osgi_3.4.0.v20080605-1900.jar
       [P2] Framework classpath:
       [P2]     file:/c:/dev/workshop/eclipseide/3.4/tools/equinox-p2-agent-3.4-win32/plugins/org.eclipse.osgi_3.4.0.v20080605-1900.jar
       [P2] Splash location:
       [P2]     null
       [P2] Debug options:
       [P2]     file:/I:/dev/workshop/eclipseide/ganymede/.options not found
       [P2] Time to load bundles: 0
       [P2] Starting application: 891
       [P2] Mirroring IU: com.perforce.p4wsad 2008.1.155919
       [P2] Mirroring artifact: canonical: com.perforce.p4wsad/osgi.bundle/2008.1.155919
       [P2] Operation completed in 2437 ms.
       [P2] Start VM: -Djava.class.path=C:\dev\workshop\eclipseide\3.4\tools\equinox-p2-agent-3.4-win32\\plugins\org.eclipse.equinox.launcher_1.0.100.v20080509-1800.jar
       [P2] -os win32
       [P2] -ws win32
       [P2] -arch x86
       [P2] -showsplash
       [P2] -launcher C:\dev\workshop\eclipseide\3.4\tools\equinox-p2-agent-3.4-win32\eclipse.exe
       [P2] -name Eclipse
       [P2] --launcher.library C:\dev\workshop\eclipseide\3.4\tools\equinox-p2-agent-3.4-win32\\plugins\org.eclipse.equinox.launcher.win32.win32.x86_1.0.100.v20080509-1800\eclipse_
1114.dll
       [P2] -startup C:\dev\workshop\eclipseide\3.4\tools\equinox-p2-agent-3.4-win32\\plugins\org.eclipse.equinox.launcher_1.0.100.v20080509-1800.jar
       [P2] -application org.eclipse.equinox.p2.tools.MirrorApplication
       [P2] -source http://www.perforce.com/downloads/http/p4-wsad/install/
       [P2] -destination file:C:/dev/workshop/eclipseide/3.4/mirrors/3rdparty
       [P2] -artifacts all
       [P2] -ius com.perforce.p4wsad/2008.1.155919
       [P2] -verbose
       [P2] -debug
       [P2] -consolelog
       [P2] -vm C:\dev\tools\sunjdk\1.6.0_04\bin\..\jre\bin\client\jvm.dll
       [P2] -vmargs
       [P2] -Djava.class.path=C:\dev\workshop\eclipseide\3.4\tools\equinox-p2-agent-3.4-win32\\plugins\org.eclipse.equinox.launcher_1.0.100.v20080509-1800.jar
[::p2-wrapper-script::] Mirror operation complete!