So this goes into tracker:

I have isolated the problem to the following change in the nx-libs
Makefile between 3.5.0.21 and 3.5.0.22, which persists through HEAD:

--- nx-libs-3.5.0.21/Makefile   2014-06-14 12:45:27.000000000 -0400
+++ nx-libs-HEAD/Makefile       2014-06-12 16:31:48.000000000 -0400
@@ -3,6 +3,7 @@
 INSTALL_DIR=install -d -m 755
 INSTALL_FILE=install -m 644
 INSTALL_PROGRAM=install -m 755
+INSTALL_SYMLINK=ln -s -f
 COPY_SYMLINK=cp -a
 RM_FILE=rm -f
 RM_DIR=rmdir -p --ignore-fail-on-non-empty
@@ -114,6 +115,13 @@
                                "$$(string_rep "$$dirname" nx-X11/.build-exports/include "$(DESTDIR)$(PREFIX)/include/nx")"/ || true; \
            done; \
 
+       # Provide means for Xinerama support in NX/X2Go sessions. This
+       # This also requires two post-install symlinks:
+       # (DESTDIR)$(NXLIBDIR)/X11/Xinerama/libNX_X11.so.6 -> /usr/<libdir>/libX11.so.6
+       # (DESTDIR)$(NXLIBDIR)/X11/Xinerama/libNX_Xext.so.6 -> /usr/<libdir>/libXext.so.6
+       $(INSTALL_DIR) $(DESTDIR)$(NXLIBDIR)/X11/Xinerama
+       $(INSTALL_SYMLINK) ../libNX_Xinerama.so.1 $(DESTDIR)$(NXLIBDIR)/X11/Xinerama/libXinerama.so.1
+
        $(INSTALL_DIR) $(DESTDIR)$(PREFIX)/include/nx/X11/bitmaps
        $(INSTALL_FILE) nx-X11/.build-exports/include/X11/bitmaps/* \
                        $(DESTDIR)$(PREFIX)/include/nx/X11/bitmaps/
 

Commenting out the Xinerama lines and rebuilding results in a clean run
of my (and your) python scripts as well as VLC player.

I have attached a diff (excepting whitespace differences (diff -ub) of
my system's Xinerama.c (xorg's libXinerama 1.1.3) and the one provided
in x2go's source (based on XFree86).

-- 
Sven Willenberger
United Pay Systems International
http://www.upsicorp.com