How to co-install forge package both stable and development versions on linux

[Tatsuro MATSUOKA]

Platform            : Ubuntu 14.04 amd 64 LTS.
Tried forge package : gsl
Issue               : overwritten "pkg install" for different version


execute octave 4.0.3 


pkg prefix /home/tatsuro/work/octave/octave-forge/4.0.3 
/home/tatsuro/work/octave/octave-forge/4.0.3
pkg install gsl-1.1.0.tar.gz


"pkg list" tells that the package is installed in 
/home/tatsuro/work/octave/octave-forge/4.0.3

After that 

execute octave 4.1.0+


pkg prefix /home/tatsuro/work/octave/octave-forge/4.1.0+ 
/home/tatsuro/work/octave/octave-forge/4.1.0+
pkg install gsl-1.1.0.tar.gz


"pkg list" tells that the package is installed in 
/home/tatsuro/work/octave/octave-forge/4.1.0+

After that

execute octave 4.0.3 

"pkg list" tells that the package is installed in 
/home/tatsuro/work/octave/octave-forge/4.1.0+

I cannot use gsl package unless re-install on octave-4.0.3.

How can I co exist gsl package for 4.0.3 and 4.1.0+?

On windows, the octave install package is self contained.
octave for packages does not interfere.

Tatsuro