175356 – graphics/libosmesa: NameError: name 'ws_dri' is not defined:

The update of port graphics/libosmesa on freeBSD 10.0-CURRENT fails with the below shown error message.

The system uses in /etc/make.conf the following X11 related flags to build new X11-software in favour of the old versions:

# New Xorg and Mesa
WITH_NEW_XORG=          YES
WITH_KMS=               YES

The build fails at the initial phase with the following error:

[...]
Mkdir("build/freebsd")
warning: gcc 4.2.x optimizer is broken -- disabling optimizations
Checking for X11 (x11 xext xdamage xfixes)... yes
Checking for XCB (x11-xcb xcb-glx >= 1.8.1)... no
Checking for XF86VIDMODE (xxf86vm)... yes
Checking for DRM (libdrm >= 2.4.24)... yes
Checking for DRM_INTEL (libdrm_intel >= 2.4.30)... yes
Checking for DRM_RADEON (libdrm_radeon >= 2.4.31)... yes
Checking for XORG (xorg-server >= 1.6.0)... yes
Checking for KMS (libkms >= 2.4.24)... no
Checking for UDEV (libudev > 150)... no
fatal: Not a git repository (or any parent up to mount point /usr/ports)
Stopping at filesystem boundary (GIT_DISCOVERY_ACROSS_FILESYSTEM not set).
Checking for C header file X11/extensions/dpmsconst.h... yes
NameError: name 'ws_dri' is not defined:
  File "/usr/ports/graphics/libosmesa/work/Mesa-9.0.1/SConstruct", line 144:
    duplicate = 0 # http://www.scons.org/doc/0.97/HTML/scons-user/x2261.html
  File "/usr/local/lib/scons-2.1.0/SCons/Script/SConscript.py", line 614:
    return method(*args, **kw)
  File "/usr/local/lib/scons-2.1.0/SCons/Script/SConscript.py", line 551:
    return _SConscript(self.fs, *files, **subst_kw)
  File "/usr/local/lib/scons-2.1.0/SCons/Script/SConscript.py", line 260:
    exec _file_ in call_stack[-1].globals
  File "/usr/ports/graphics/libosmesa/work/Mesa-9.0.1/src/SConscript", line 34:
    SConscript('gallium/SConscript')
  File "/usr/local/lib/scons-2.1.0/SCons/Script/SConscript.py", line 614:
    return method(*args, **kw)
  File "/usr/local/lib/scons-2.1.0/SCons/Script/SConscript.py", line 551:
    return _SConscript(self.fs, *files, **subst_kw)
  File "/usr/local/lib/scons-2.1.0/SCons/Script/SConscript.py", line 260:
    exec _file_ in call_stack[-1].globals
  File "/usr/ports/graphics/libosmesa/work/Mesa-9.0.1/src/gallium/SConscript", line 148:
    'targets/dri-vmwgfx/SConscript',
  File "/usr/local/lib/scons-2.1.0/SCons/Script/SConscript.py", line 614:
    return method(*args, **kw)
  File "/usr/local/lib/scons-2.1.0/SCons/Script/SConscript.py", line 551:
    return _SConscript(self.fs, *files, **subst_kw)
  File "/usr/local/lib/scons-2.1.0/SCons/Script/SConscript.py", line 260:
    exec _file_ in call_stack[-1].globals
  File "/usr/ports/graphics/libosmesa/work/Mesa-9.0.1/src/gallium/targets/dri-swrast/SConscript", line 11:
    ws_dri,
*** [do-build] Error code 2

Stop in /usr/ports/graphics/libosmesa.

===>>> make failed for graphics/libosmesa
===>>> Aborting update

How-To-Repeat: Update port graphics/libosmesa. The update fails on systems FreeBSD 10 and FreeBSD 9.1-STABLE with new Xorg set (having those flags NOT set is not tested since we do not have such systems anymore).