Is it possible to change the content of a snapshot created by a build result during the build?

As Nick commented:

but there's currently no way of associating an arbitrary snapshot with the build result in the same way as the original snapshot

We wrote an Ant task that allows one to associate a snapshot to a build result. The task works, but once we started using the task we started experiencing this temporarily missing snapshot problem. EDIT: The issue has been resolved and the code below was updated to correct the issue. In certain cases, we associate the same snapshot to more than one build result (e.g. rebuild scenarios). The first time we associate the snapshot to the build result, all works fine. But, subsequent attempts sometimes fail where the server tells us that the item is no longer available. After some time, later attempts for the same item will work. Perhaps our Ant task is putting the snapshot into a temporary bad state?

The body of the Ant task is:

IBaselineSet snapshot = getSnapshot(this.snapshotUUID, getTeamRepository(),
    getProgressMonitor());
addSnapshotContributionToBuild(snapshot, getBuildResult(
    IBuildResult.PROPERTIES_COMPLETE), getTeamRepository(), getProgressMonitor());

The body of the Ant task uses these two methods:

private IBaselineSet getSnapshot(String snapshotUuid,
        ITeamRepository teamRepository, IProgressMonitor progressMonitor)
        throws TeamRepositoryException {
    IBaselineSetHandle baselineSetHandle = (IBaselineSetHandle)
        IBaselineSet.ITEM_TYPE.createItemHandle(UUID.valueOf(snapshotUuid), null);
    return (IBaselineSet) teamRepository.itemManager().fetchCompleteItem(
        baselineSetHandle, IItemManager.REFRESH, progressMonitor);
}

public void addSnapshotContributionToBuild(IBaselineSet snapshot,
        IBuildResult buildResult, ITeamRepository teamRepository,
        IProgressMonitor progressMonitor)
        throws TeamRepositoryException {
    IBuildResultContribution contribution =
        BuildItemFactory.createBuildResultContribution();
    contribution.setExtendedContributionTypeId(
            ScmConstants.EXTENDED_DATA_TYPE_ID_BUILD_SNAPSHOT);
    contribution.setImpactsPrimaryResult(false);
    contribution.setLabel(NLS.bind(
            AntMessages.TeamAcceptTask_SNAPSHOT_CONTRIBUTION_LABEL,
                snapshot.getName()));
    contribution.setExtendedContribution(snapshot);
    ITeamBuildClient buildClient = ClientFactory.getTeamBuildClient(teamRepository);
    buildClient.addBuildResultContribution(buildResult, contribution,
        progressMonitor);
}