[migration] re-try without print_function when compiling a script fails
As part of the python3 porting we added the __future__.print_function import to
cubicweb.migration. That started affecting all migration scripts it runs,
which may not be prepared. So if compiling a script results in SyntaxError,
try again without the print_function flag.
Closes #7935030
usr/lib/python2*/*-packages/cubicweb/entities/
usr/lib/python2*/*-packages/cubicweb/ext/
usr/share/cubicweb/cubes/
usr/lib/python2*/*-packages/cubicweb/*.py