[yocto] Incremental rebuild doesn't pick up FILES changes.

[Kaz Kylheku (poky)]

Hi,

I'm working in a Yocto 2.5 environment.

In my own layer, I added a bbappend targeting python which does this:

   FILES_${PN}_remove = "${libdir}/python2.7/encodings"

Now this didn't take effect as I expected. I had to do a "bitbake -c 
cleanall python" to rebuild the package.

In any case, all I have in the image now, as I expected, is these four 
files, vastly reduced from dozens:

   /usr/lib/python2.7/encodings/{aliases,utf-8}.{py,pyc}

Now, if I comment out this FILES_${PN}_remove variable assignment, I 
cannot get the previously removed encoding modules to re-appear in my 
image! I tried "bitbake -c cleanall" on python, and blowing away its 
build directory. It didn't work; still there are just those four files.

How do we get Yocto to react to FILES changes, short of blowing away the 
entire build tree?