"'What is going on whenever someone changes code is that they
make a 'derivative work',' began Theodore Ts'o. 'Whether or not you
can even make a derivative work, and under what terms the
derivative work can be licensed, is strictly up to the license of
the original. For example, the BSD license says: 'redistribution
and use in source and binary forms, with or without modification,
are permitted provided that the following conditions are met....'
Note the 'with or without modification'. This is what allows people
to change BSD licensed code and redistribute said changes.'
Regarding code that is GPL'd, he added, 'it is not a relicencing,
per se, since the original version of the file is still available
under the original copyright; it is only the derived work which is
under the more restrictive copyright...'"