The sed manpage fails to document lots of stuff, and there seem to be better versions available. For example, it doesn't document //I syntax for case insensitive matching, nor does it document s///FLAGS g, even.
The behaviour of \0 is also undocumented.
-i[SUFFIX], --in-place[=SUFFIX]
edit files in place (makes backup if extension supplied)
Should be read as
Applied upstream, thanks (commit dd275ee12aa73447748f269df2c899635a43e15b). Paolo