Yes, I'm very aware of our license.
It allows people to link it in their non-free, proprietary software without any vitality on that proprietary software. It still requires them to make the source for the version of libgit2 that they are using available upon request.
> In addition to the permissions in the GNU General Public License, the authors give you unlimited permission to link the compiled version of this library into combinations with other programs, and to distribute those combinations without any restriction coming from the use of this file. [...]
https://github.com/libgit2/libgit2/blob/master/COPYING