Unlicensing Contributions

In order to ensure your project remains completely free and unencumbered by anyone's copyright monopoly, it is advisable to explicitly dedicate major code-base contributions to the public domain.

This removes any possible ambiguity as to what terms somebody might have thought they were contributing under, in case of a future dispute. These concerns are not unique to public domain software.

Most large, established open-source projects have a Contributor License Agreement (CLA) process, of varying degrees of formality.

You can accompany any non-trivial patches with a simple statement like the following:

I dedicate any and all copyright interest in this software to the public domain. I make this dedication for the benefit of the public at large and to the detriment of my heirs and successors. I intend this dedication to be an overt act of relinquishment in perpetuity of all present and future rights to this software under copyright law.