Cannot set BYMONTHDAY to a comma-separated list

[joelstein]

I'm using version 0.17.0 and cannot set the BYMONTHDAY to a comma-separated list.

The spec says:

The BYMONTHDAY rule part specifies a COMMA-separated list of days of the month.

This sentence is actually at the top of RecurrenceRule::setByMonthDay(). But the function throws the following error if the $day param is something like '2,3,4,5,6,7,8':

Invalid value for BYMONTHDAY