bin/52210: The recent change to ksh(1)'s misc.c breaks traditional parameter substitution behaviour

[dhgutteridge%sympatico.ca@localhost]

>Number:         52210
>Category:       bin
>Synopsis:       The recent change to ksh(1)'s misc.c breaks traditional parameter substitution behaviour
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    bin-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue May 02 23:50:00 +0000 2017
>Originator:     David H. Gutteridge
>Release:        HEAD as of May 2, 2017
>Organization:
>Environment:
NetBSD arcus-v3.nonus-porta.net 7.99.71 NetBSD 7.99.71 (GENERIC) #0: Tue May  2 08:20:20 UTC 2017  mkrepro%mkrepro.NetBSD.org@localhost:/usr/src/sys/arch/amd64/compile/GENERIC amd64

>Description:
Revision 1.16 of src/bin/ksh/misc.c breaks some traditional ksh(1)
parameter substitution behaviour, e.g.:

From source prior to the change:

[disciple@arcusiii:disciple]$ echo $PWD
/home/disciple
[disciple@arcusiii:disciple]$ echo ${PWD##*/} 
disciple

From source after the change:

[disciple@arcus-v3:disciple]$ echo $PWD
/home/disciple
[disciple@arcus-v3:disciple]$ echo ${PWD##*/} 
/home/disciple

(I'm assuming this wasn't intended, but if it was, then the ksh(1) man
page needs updating as well.)

>How-To-Repeat:
Try "echo ${PWD##*/}" on a recent build.
>Fix: