Bug#615476: general: many binaries are linked with non-existent libtiff.so.3 library
I also reported this problem to gnuplot's maintainers as bug #615289 before I found how many programs is depend on libtiff.so.3 on my system.
With Julien's help I have discovered that gnuplot gets dependencies from old libraries in /usr/local:
$ ldd /usr/bin/gnuplot | grep /usr/local
libwx_gtk2u_core-2.8.so.0 => /usr/local/lib/libwx_gtk2u_core-2.8.so.0 (0xb7bad000)
libwx_baseu-2.8.so.0 => /usr/local/lib/libwx_baseu-2.8.so.0 (0xb7a60000)
Programs in /usr/local are too important for me so I can't delete them. I found the next solution:
$ export LD_LIBRARY_PATH=/lib:/usr/lib
Then gnuplot runs normally in this terminal session.
Is it normal that Debian's programs in my system gets dependencies from non-Debian libraries?
In this situation each new installation in /usr/local is a venture with unpredictable results.
Any Debian's program can stop work or can begin work in unexpected way after installation of new program in /usr/local. It makes Debian unreliable system.