Do not fail SUBSCRIBEs that start in the past

draft-ietf-moq-transport.md

@@ -1342,14 +1342,14 @@ the subscription starts with the first published or received group.
 
 AbsoluteStart (0x3):  Specifies an open-ended subscription beginning
 from the object identified in the StartGroup and StartObject fields. If the
-StartGroup is prior to the current group, the publisher MUST reply with a
-SUBSCRIBE_ERROR with code 'Invalid Range'.
+StartGroup is prior to the current group, the subscription starts at the
+beginning of the current object like the 'Latest Object' filter.
 
 AbsoluteRange (0x4):  Specifies a closed subscription starting at StartObject
 in StartGroup and ending at EndObject in EndGroup.  The start and end of the
 range are inclusive.  EndGroup MUST specify the same or a later group than
-StartGroup. If the StartGroup is prior to the current group, the publisher MUST
-reply with a SUBSCRIBE_ERROR with code 'Invalid Range'.
+StartGroup. If the StartGroup is prior to the current group, the subscription
+starts at the beginning of the current object like the 'Latest Object' filter.
 
 A filter type other than the above MUST be treated as error.