From the release notes:
R52b is a strongly recommended bugfix-only release:
[tg] Recognise ksh93 compiled scripts and LZIP compressed files as binary (i.e. to not run as mksh plaintext script)
[tg] Document that we will implement locale tracking later
[tg] Add EEXIST to failback strerror(3)
[jilles] Make set -C; :>foo race-free
[tg] Don’t use unset in portable build script
[tg] Plug warning on GNU/kFreeBSD, GNU/Hurd
[tg] Document read -a resets the integer base
[J�rg] Fix manpage: time is not a builtin but a reserved word
[J�rg, tg] Make exit (and return) eat -1
[tg] parse “$( (( … ) … ) … )” correctly (LP#1532621), Jan Palus
[tg] reduce memory footprint by free(3)ing more aggressively
[tg] fix buffer overrun (LP#1533394), bugreport by izabera
[tg] correctly handle nested ADELIM parsing (LP#1453827), Teckids
[tg] permit “read -A/-a arr[idx]” as long as only one element is read; fix corruption of array indicēs with this construct (LP#1533396), izabera
[tg] Sanitise OS-provided signal number in even more places
[tg] As requested by J�rg, be clear manpage advice is for mksh
[tg] Revert (as it was a regression) POSIX bugfix from R52/2005 related to accent gravis-style command substitution until POSIX decides either way
[tg] Handle export et al. after command (Austin#351)
[tg] Catch EPIPE in built-in cat and return as SIGPIPE (LP#1532621)
[tg] Fix errno in print/echo builtin; optimise that and unbksl
[tg] Update documentation, point out POSIX violation (Austin#1015)
R52 is a strongly recommended bugfix release:
[_0bitcount] Move moving external link from mksh(1) to the #ksh channel homepage linked therein
[tg] Make setenv “set -u”-safe and fix when invoked with no args
[tg] Make “typeset -f” output reentrant if name is a reserved word
[oksh] Zero-pad seconds in “time” output to align columns
[tg] Check signals and errorlevels from OS to be within bounds
[komh, tg] Quote and document ‘;’ as PATH separator in some places
[oksh, tg] Simplify code to call afree() even if arg is NULL
[tg] Fix tree-printing and reentrancy of multiple here documents
[tg] Work around LP#1030581 by permitting exactly one space after
[tg, oksh] Code quality work, cleanups
[tg] New code for here documents/strings with several bugfixes
[tg] Stop using issetugid(2) for ±p checks, wrong tool for the job
[tg] Reintroduce some -o posix changes lost in 2005, plus fixes
[tg] Make “source” into a built-in command
[tg] Drop “stop” alias, lksh(1) functionality to auto-unalias
[tg] Fix \u0000 ignored in $'…' and print
[tg] Improve portability of Build.sh
[Jilles Tjoelker] Improve portability of testsuite
[tg] Fix tilde expansion for some substitutions (izabera, Chet, Geoff)
[tg] Improve reparsing of ((…) |…) as ( (…) |…)
[Martijn Dekker] Fix test(1) not returning evaluation errors
[tg] Fix ${*:+x} constructs (carstenh)
[tg] Make (( … )) into a compound command (ormaaj)
[tg] Repair a few parameter substitution expansion mistakes
Change-Id: I3d875b5c648c60cc6203c964f11d8cbd42648d9c