install_name_tool changes not propagating on distribution

Question

I am wrapping a python GUI into an application using py2app. On porting to another machine I noticed that I was having a dependency issue with libpng12.0.dylib. This is stored provided by the system, with X11, and is therefore not traditionally bundled by py2app.

Another dylib (which is bundled) requires a newer version of libpng. Using the commands below I attempted to link to a copy of libpng that I will include with the OS X. This works wonderfully locally, but when I attempt to copy the app, it reverts to the old path. The commands below should explain this better.

Copy my libpng to the Framework directory of my app.

cp /usr/X11/lib/libpng12.0.dylib dist/PyStretch.app/Contents/Frameworks/

Look at the paths of the dependencies of libgdal.1.dylib (which requires the newer libpng)

   mbp:pystretch drferling$ otool -L   
   dist/PyStretch.app/Contents/MacOS/../Frameworks/libgdal.1.dylib 
   dist/PyStretch.app/Contents/MacOS/../Frameworks/libgdal.1.dylib:
   @executable_path/../Frameworks/libgdal.1.dylib (compatibility version 18.0.0, current version 18.1.0)
    ...CLIPPED
    /usr/X11/lib/libpng12.0.dylib (compatibility version 47.0.0, current version 47.0.0)
    @executable_path/../Frameworks/libcfitsio.dylib (compatibility version 0.0.0, current version 0.0.0)

So libpng is linked to a system install. We need to change that to be linked to a local (to the app) installation.

install_name_tool -change /usr/X11/lib/libpng12.0.dylib @executable_path/../Frameworks/libpng12.0.dylib dist/PyStretch.app/Contents/MacOS/../Frameworks/libgdal.1.dylib

We then need to verify that that worked.

mbp:pystretch drferling$ otool -L 
dist/PyStretch.app/Contents/MacOS/../Frameworks/libgdal.1.dylib dist/PyStretch.app/Contents/MacOS/../Frameworks/libgdal.1.dylib:
@executable_path/../Frameworks/libgdal.1.dylib (compatibility version 18.0.0, current version 18.1.0)
...CLIPPED
@executable_path/../Frameworks/libpng12.0.dylib (compatibility version 47.0.0, current version 47.0.0)
@executable_path/../Frameworks/libcfitsio.dylib (compatibility version 0.0.0, current version 0.0.0)

So it worked. libpng is now linked to the included copy, not the system copy.

I then copy the app over to another machine for testing and the libpng reverts to being statically linked to the system installation of libpng!

Why?

I also tried using install_tool_name -id, but the results are the same. The linking of my dylib keeps changing when I copy the app to another machine.