[TxMt] 'Documentation for word' command in ruby broken?

When I try and use the 'Documentation for word' command (control h) I now get the error message:

.../lib/web_preview.rb:6 in 'html_header' : undefined method url_encode for ERB::Util:Module (No Method Error) from tmp/ temp_textmate_Qp8b1:19

This has worked in the past and the only thing that I believe has changed since it was working is the version of Textmate (now at 1.5.3 (1258)).

Nothing in the svn bundle logs on the RSS feed looked like it related to this. I have removed all my customization by getting rid of the Bundles folder in ~/Library/Application Support/TextMate with no effect and there is no TextMate folder in /Library/ Application Support.

Dave.