function checkLocationConstraint(request, locationConstraint, log) {
    // AWS JS SDK sends a request with locationConstraint us-east-1 if
    // no locationConstraint provided.
    const { parsedHost } = request;
    let locationConstraintChecked;
    let locationConstraintAddon;
    if (locationConstraint) {
        locationConstraintAddon = locationConstraint.split(zenkoSeparator)[1];
        locationConstraintChecked = locationConstraint.split(zenkoSeparator)[0];
    } else if (parsedHost && restEndpoints[parsedHost]) {
        locationConstraintChecked = restEndpoints[parsedHost];
    } else {
        log.trace('no location constraint provided on bucket put;' +
            'setting us-east-1');
        locationConstraintChecked = 'us-east-1';
    }

    if (!locationConstraints[locationConstraintChecked]) {
        const errMsg = 'value of the location you are attempting to set - ' +
            `${locationConstraintChecked} - is not listed in the ` +
            'locationConstraint config';
        log.trace(`locationConstraint is invalid - ${errMsg}`,
            { locationConstraint: locationConstraintChecked });
        return { error: errorInstances.InvalidLocationConstraint.
            customizeDescription(errMsg) };
    }
    if (locationConstraints[locationConstraintChecked].isCold) {
        return { error: errors.InvalidLocationConstraint };
    }
    if (locationConstraintAddon) {
        // We are introducing a new format for location constraints.
        // with `zenkoSeparator`, we are currently including the ingestion
        // flag in the location constraint.
        locationConstraintChecked = locationConstraint;
    }
    return { error: null, locationConstraint: locationConstraintChecked };
}
checkLocationConstraint - check that a location constraint is explicitly
set on the bucket and the value of the location is listed in the
locationConstraint config.
Note: if data backend equals "multiple", you must set a location constraint
@param {object} request - http request object
@param {string} locationConstraint - the location constraint sent with
the xml of the request
@param {object} log - Werelogs logger
@return {undefined}