toolchain/50022: NetBSD 4.x can't build NetBSD 7.x

[Simon Burge <simonb%NetBSD.org@localhost>]

>Number:         50022
>Category:       toolchain
>Synopsis:       NetBSD 4.x can't build NetBSD 7.x
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    toolchain-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Jul 02 08:35:00 +0000 2015
>Originator:     Simon Burge
>Release:        NetBSD 4.0_STABLE
>Organization:
>Environment:
	System: NetBSD thoreau.thistledown.com.au 4.0_STABLE NetBSD 4.0_STABLE (THOREAU-4) #7: Sun Sep 21 17:57:39 EST 2008 simonb%thoreau.thistledown.com.au@localhost:/usr/obj/sys/arch/i386/compile/THOREAU-4 i386
	Architecture: i386
	Machine: i386
>Description:
	Running build.sh on a netbsd-7 branch source tree from 02 July 2015
	gets an error trying to build the tools version of file:


	dependall ===> tools/file
	  [ ... ]
	checking whether /NetBSD/build7/tools/bin/nbmake supports nested variables... yes
	usage: rm [-f|-i] [-dPRrvW] file ...
	Oops!

	Your 'rm' program seems unable to run without file operands specified
	on the command line, even when the '-f' option is present.  This is contrary
	to the behaviour of most rm programs out there, and not conforming with
	the upcoming POSIX standard: <http://austingroupbugs.net/view.php?id=542>

	  [ ... ]

	configure: error: Your 'rm' program is bad, sorry.

	  [ ... ]

	Stop.
	nbmake[6]: stopped in /NetBSD/src7/tools/file

>How-To-Repeat:
	./build.sh ...
>Fix:
	NFI.  Must have been the leap second yesterday?!