Fix ck_assert_msg() call

[opoplawski]

No description provided.

[micahsnyder]

Thanks for the PR, good fix. :) I'll stage this to be merged on our internal repo.

[micahsnyder]

@opoplawski just merged this: 2b46876...dce04e5

Thanks again!

[rma-x]

It looks like this fix only made it into 0.104, but I think it should also be in 0.103.
And maybe it would have been better to use ck_abort_msg() instead of calling ck_assert_msg() with a constant expression.