Correct a bitrotted comment about installworld order requirements.

The case of make(1) using a new /bin/sh issue was fixed in r173219 when ITOOLS
was introduced.

There are still issues with mid-install errors leaving a system unusable that
are currently non-trivial to solve.  The safest ordering requires installing
rtld, libc and libthr (in that order) before anything else.  We don't do that
now though.  Much improvement is needed here still.

Discussed with:	kip and kan (rtld/library ordering)
MFC after:	1 week
Sponsored by:	EMC / Isilon Storage Division

1 files changed, 8 insertions, 5 deletions

diff --git a/Makefile.inc1 b/Makefile.inc1
index 256a6f81a137..8b54edf4c457 100644
--- a/Makefile.inc1
+++ b/Makefile.inc1
@@ -50,11 +50,14 @@
 .include <bsd.arch.inc.mk>
 .include <bsd.compiler.mk>
 
-# We must do lib/ and libexec/ before bin/, because if installworld
-# installs a new /bin/sh, the 'make' command will *immediately*
-# use that new version.  And the new (dynamically-linked) /bin/sh
-# will expect to find appropriate libraries in /lib and /libexec.
-#
+# We must do lib/ and libexec/ before bin/ in case of a mid-install error to
+# keep the users system reasonably usable.  For static->dynamic root upgrades,
+# we don't want to install a dynamic binary without rtld and the needed
+# libraries.  More commonly, for dynamic root, we don't want to install a
+# binary that requires a newer library version that hasn't been installed yet.
+# This ordering is not a guarantee though.  The only guarantee of a working
+# system here would require fine-grained ordering of all components based
+# on their dependencies.
 SRCDIR?=	${.CURDIR}
 .if defined(SUBDIR_OVERRIDE)
 SUBDIR=	${SUBDIR_OVERRIDE}