Printing Unicode escapes with 6 digits may be problematic
A recent R-devel commit introduces a change in the way non-printable Unicode characters are shown as an escape code. Whereas large code points were previously printed using an escape code of 8 hexadecimal digits, with initial zeros, the present code (tested with R-devel r79623 on Ubuntu Linux) only prints 6 hex digits. I think this may be problematic: it is now possible that R prints a character string which is not valid when reused as an input. See the following example.