Bug 117493 [content assist] CompletionRequestor#completionFailure(IProblem)) is ignored
This got introduced after 3.2 M1 (i.e. broken in 3.2 M2 and newer). If completion fails we now always show: "No completion available." instead of the real error text. Example: for (Iterator i=things.iterator(); i.<ctrl-space> // Iterator not yet imported)
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/text/java/CompletionProposalComputerDescriptor.java
* Safely computes completion proposals through the described extension. If the extension
	 * is disabled, throws an exception or otherwise does not adhere to the contract described in
	 * {@link ICompletionProposalComputer}, an empty list is returned.
	 * 
	 * @param context the invocation context passed on to the extension
	 * @param monitor the progress monitor passed on to the extension
	 * @return the list of computed completion proposals (element type:
	 *         {@link org.eclipse.jface.text.contentassist.ICompletionProposal})
	 */
	public List computeCompletionProposals(TextContentAssistInvocationContext context, IProgressMonitor monitor) {
		if (!isEnabled())
			return Collections.EMPTY_LIST;
		
		IStatus status;
		try {
			ICompletionProposalComputer computer= getComputer();
			
			PerformanceStats stats= startMeter(context, computer);
			List proposals= computer.computeCompletionProposals(context, monitor);
			stopMeter(stats, COMPUTE_COMPLETION_PROPOSALS);
			
			if (proposals != null)
				return proposals;
			
			status= createAPIViolationStatus(COMPUTE_COMPLETION_PROPOSALS);
		} catch (InvalidRegistryObjectException x) {
			status= createExceptionStatus(x);
		} catch (CoreException x) {
			status= createExceptionStatus(x);
		} catch (RuntimeException x) {