repositoryVersions.put(repository.getUniqueId(), ImmutableSet.copyOf(versions));
    }

    @Nullable
    public File getWorkingDirForRevision(VersionControlRepositoryConnection repository, VersionRef version) {
        String cacheKey = versionCacheKey(repository, version);
        return checkoutDirs.get(cacheKey);
    }

        // TODO - prevent multiple threads from performing the same VCS populate operation at the same time
        File workingDir = inMemoryCache.getWorkingDirForRevision(repository, selectedVersion);
        if (workingDir == null) {
            workingDir = repository.populate(selectedVersion);
            inMemoryCache.putWorkingDirForRevision(repository, selectedVersion, workingDir);