R50f is a required security and bugfix release:
* Add a patch marker for vendor patch versioning to mksh.1
* SECURITY: make unset HISTFILE actually work
* Document some more issues with the current history code
* Remove some unused code
* RCSID-only sync with OpenBSD, for bogus and irrelevant changes
* Also disable field splitting for alias ‘local= ypeset’
* Fix read -n-1 to not be identical to read -N-1
* Several fixes and improvements to lksh(1) and mksh(1) manpages
* More code (int → size_t), comment and testsuite fixes
* Make dot.mkshrc more robust (LP#1441853)
* Fix issues with IFS=” read, found by edualbus
* Fix integer overflows related to file descriptor parsing, found by Pawel Wylecial (LP#1440685); reduce memory usage for I/O redirs
* Document in the manpage how to set ±U according to the current locale settings via LANG/LC_* parameters (cf. Debian #782225)
* Some code cleanup and restructuring
* Handle number parsing and storing more carefully