Installation on Eclipse 3.5.1 fails in Ubuntu

Clean install of Ubuntu, and clean install of Eclipse from Ubuntu's package manager.

Pointing to the Development Build update site for 3.5 ( http://dist.codehaus.org/groovy/distributions/greclipse/snapshot/e3.5/) yields the following error:

Cannot complete the install because of a conflicting dependency.
Software being installed: Groovy-Eclipse Feature 2.0.0.xx-20091104-1700-e35 (org.codehaus.groovy.eclipse.feature.feature.group 2.0.0.xx-20091104-1700-e35)
Software currently installed: Eclipse Platform 3.5.1 (Eclipse Platform 3.5.1)
Only one of the following can be installed at once:
Java Development Tools Core 3.5.1.v_972_R35x (org.eclipse.jdt.core 3.5.1.v_972_R35x)
Java Development Tools Core 3.5.1.xx-20091104-1700-e35 (org.eclipse.jdt.core 3.5.1.xx-20091104-1700-e35)
Cannot satisfy dependency:
From: Eclipse Platform 3.5.1 (Eclipse Platform 3.5.1)
To: org.eclipse.jdt.core [3.5.1.v_972_R35x]
Cannot satisfy dependency:
From: Eclipse Platform 3.5.1 (Eclipse Platform 3.5.1)
To: org.eclipse.jdt.feature.group [3.5.1.r351_v20090810-0600-7r88FEoFHxXYpY3s0jOJPn58EpLN]
Cannot satisfy dependency:
From: Groovy-Eclipse Feature 2.0.0.xx-20091104-1700-e35 (org.codehaus.groovy.eclipse.feature.feature.group 2.0.0.xx-20091104-1700-e35)
To: org.codehaus.groovy.jdt.patch.feature.group [2.0.0.xx-20091104-1700-e35]
Cannot satisfy dependency:
From Patch: org.codehaus.groovy.jdt.patch.feature.group 2.0.0.xx-20091104-1700-e35 Eclipse Java Development Tools 3.5.1.r351_v20090810-0600-7r88FEoFHxXYpY3s0jOJPn58EpLN (org.eclipse.jdt.feature.group 3.5.1.r351_v20090810-0600-7r88FEoFHxXYpY3s0jOJPn58EpLN)
To: org.eclipse.jdt.core [3.5.1.xx-20091104-1700-e35]