Created attachment 590082 [details] build log Log attached
Created attachment 590084 [details] emerge info
Something is causing lib2to3 to regenerate the pickle files. There is probably a weird timestamp on one of the source files. Please tar up the /usr/lib64/python3.6/lib2to3 directory and attach it.
By recompiling python3 the issue does not happen anymore, so I guess something weird here.
(In reply to Agostino Sarubbo from comment #3) I was hoping to inspect the files before you rebuilt python3.6, so we could know for sure what the problem was.
Created attachment 590360 [details] lib2to3.tar.xz No problem, I made a tar before recompile.