Comment 0 for bug 1087319

Quoter::seralize_list() dies on multiple NULL values because at first we could represent multiple NULLs because <,> could be two empty strings or two NULLs., and <NULL,NULL> could be two literal string values of "NULL". But there is a way to do this: MySQL does it when it writes outfiles (SELECT INTO OUTFILE) by representing \N as NULL (so \\N is a literal "\N" string).