I use most recent version of WPT and regularly update it from trunk using SVN client.
When I noticed some issues after upgrading do SVN 1.7 with externals (files update.zip and update.ini in work/update directory) I just downgraded do 1.6 version some time ago.
Since some time ago these two have not been versioned.
Is it possible to return to this very convenient way of ting agent versions to WPT server versions?
AFAIK it is problem with defining files as externals inside another external.
What I suggest is to just put those files in repository under dist\webpagetest\www\work\update path or to set entire update directory as external at for example dist level.