Error with LD_PRELOAD

Hi
Since new update/upgrade I am unable, with debian amd64 stretch, to preload
a library that lies on the same folder from which I am working. What has
changed in amd64 stretch that does no more finds the library and looks
elsewhere for a non-existing library? Commands below:

> francesco@vaio64:~/servers/cineca/RCM_remote_visualization$
> LD_PRELOAD=/home/francesco/servers/cineca/RCM_remote_visualization/libX11.so.6
> /bin/ls
> libX11.so.6  RCM_linux_64bit
> francesco@vaio64:~/servers/cineca/RCM_remote_visualization$ export
> LD_PRELOAD=/home/francesco/tmp/libX11.so.6
> francesco@vaio64:~/servers/cineca/RCM_remote_visualization$ ldd /bin/ls
> ERROR: ld.so: object '/home/francesco/tmp/libX11.so.6' from LD_PRELOAD
> cannot be preloaded (cannot open shared object file): ignored.
> ERROR: ld.so: object '/home/francesco/tmp/libX11.so.6' from LD_PRELOAD
> cannot be preloaded (cannot open shared object file): ignored.
>     linux-vdso.so.1 (0x00007ffefd181000)
>     libselinux.so.1 => /lib/x86_64-linux-gnu/libselinux.so.1
> (0x00007f01458d9000)
>     libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f014553a000)
>     libpcre.so.3 => /lib/x86_64-linux-gnu/libpcre.so.3 (0x00007f01452c7000)
>     libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f01450c3000)
>     /lib64/ld-linux-x86-64.so.2 (0x00007f0145d22000)
>     libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0
> (0x00007f0144ea6000)
> francesco@vaio64:~/servers/cineca/RCM_remote_visualization$
>

Therefore, I am unable, at this point, to launch a program for remote
visualization (which worked well before the said update/upgrade):

> francesco@vaio64:~/servers/cineca/RCM_remote_visualization$
> ./RCM_linux_64bitERROR: ld.so: object '/home/francesco/tmp/libX11.so.6'
> from LD_PRELOAD cannot be preloaded (cannot open shared object file):
> ignored.
> ERROR: ld.so: object '/home/francesco/tmp/libX11.so.6' from LD_PRELOAD
> cannot be preloaded (cannot open shared object file): ignored.
> Traceback (most recent call last):
>   File "<string>", line 10, in <module>
>   File
> "/home/vagrant/devel/RCM/multivnc/PyInstaller/PyInstaller-2.1/PyInstaller/loader/pyi_importers.py",
> line 270, in load_module
>   File "/tmp/build/rcm_client_tk/out00-PYZ.pyz/Tkinter", line 39, in
> <module>
>   File
> "/home/vagrant/devel/RCM/multivnc/PyInstaller/PyInstaller-2.1/PyInstaller/loader/pyi_importers.py",
> line 409, in load_module
> ImportError: /usr/lib/x86_64-linux-gnu/libX11.so.6: undefined symbol:
> xcb_poll_for_reply64
>

Grateful for advice
francesco pietra