def replace(self, old_patch, new_patch):
        """ Replace old_patch with new_patch
        The method only replaces the patch and doesn't change any comments.
        """
        self._check_patch(old_patch)
        old_patchline = self.patch2line[old_patch]
        index = self.patchlines.index(old_patchline)
        self.patchlines.pop(index)
        new_patchline = PatchLine(new_patch)
        new_patchline.set_comment(old_patchline.get_comment())
        self.patchlines.insert(index, new_patchline)
        del self.patch2line[old_patch]
        self.patch2line[new_patch] = new_patchline
Replace old_patch with new_patch
        The method only replaces the patch and doesn't change any comments.