The space after the newline is used to fold long lines in the iCalendar files. It probably is not what's causing the issue but you can try this by entering a long summary for a new event and it should be split in multiple lines too the same way.
What could be the reason for the parsing failure is the escaped quotes in the X-RAINLENDAR-CALDAV-ETAG. There is an old bug reported about it: trac.calendarserver.org/ticket/419
Check what the value of the INVALID_ESCAPE_SEQUENCES is in the server's parser.py
file. If it is PARSER_RAISE try changing it to PARSER_FIX, restart the server and see if that helps.