1. Summarise the issue (what were doing, what went wrong?)
GPL license is incompatible with other software and also requires me to
hire a professional lawyer to start reusing and enhancing the code for
my commercial projects. Besides, there are not many lawyers, who are
able to fully understand the implications of GPL. 

While that is completely up to the authors to choose the license and I
highly appreciate their work and the fact that darcs is available for
the public, I can see no benefit in using obscure stuff like GPL. Either
make it free or not? 

2. What behaviour were you expecting instead?
Any straightforward license. BSD? MIT? ISC?

3. What darcs version are you using? (Try: darcs --exact-version)
Any

4. What operating system are you running?
Any