code: func unsetenvGPGAgentInfo() {
  	v := C.CString("GPG_AGENT_INFO")
  	defer C.free(unsafe.Pointer(v))
  	C.unsetenv(v)
  }
docs: // This is somewhat of a horrible hack. We need to unset GPG_AGENT_INFO so that gpgme does not pass --use-agent to GPG.
  // os.Unsetenv should be enough, but that only calls the underlying C library (which gpgme uses) if cgo is involved
  // - and cgo can't be used in tests. So, provide this helper for test initialization.