Recent build failures -- a connection with tty/sh revisions? C library changes?

I'm seeing some strange behavior on 8-CURRENT amd64 r189705 that
has only started to occur in the last few days.  Looking back at
recent revisions, I'm guessing that it is most likely to be
related to either ed_at_'s recent tty/sh changes, or das_at_'s changes
to various library routines on Mar. 4 -- but these are only
guesses, and I would be glad to hear if anyone else has seen it
and tracked it down. The problem results in build breakages as
some, but not all, path names in scripts are expanded
improperly.  For example:

"...

 install  -o root -g wheel -m 444 'xtypes.py' '/usr/local/lib/python2.6/site-packages/xcbgen/xtypes.py'
Byte-compiling python modules...
__init__.py error.py expr.py matcher.py state.py xtypes.py
Byte-compiling python modules (optimized versions) ...
__init__.py error.py expr.py matcher.py state.py xtypes.py
make: /tmp/usrs/x11/xcb-proto/work/xcb-proto-1.4: No such file or directory
*** Error code 1

Stop in /tmp/usr/ports/x11/xcb-proto/work/xcb-proto-1.4.
*** Error code 1"


Here /tmp/usr/ports/ has been transmogrified into /tmp/usrs/,
which doesn't exist; or:

"...

 install  -o root -g wheel -m 444 'Compose' '/usr/local/lib/X11/locale/zh_TW.UTF-8/Compose'
make: /tmp/usr/x11/libX11/work/libX11-1.2/nls: No such file or directory
*** Error code 1"

where /tmp/usr/ports/x11... has become /tmp/usr/x11... ; or:

"...

Looking for apr source in /tmp/usr/ports/devel/apr/work/apr-1.3.3
Creating include/private/apu_config.h ...
cannot stat initial working directory for /tmp/usrs/devel/apr/work/apr-util-1.3.4: No such file or directory at /usr/local/share/autoconf-2.62/Autom4te/General.pm line 197
*** Error code 1

Stop in /usr/ports/devel/apr.
*** Error code 1"

where an error similar to the first example has occurred.
Apparently, I'm not the only one experiencing this problem, as
someone has just filed a PR that seems to be another instance of
this behavior:

http://www.freebsd.org/cgi/query-pr.cgi?pr=ports/132542


Any suggestions?

Regards,
         b.