Not sure why this happens, but I would suggest to use an URL which never changes (eg. based on a tarball for a specific version). Just to make it more failsave.
However, I'm not the owner of this recipe, so not my decision to do that.
File 4123e6579309cd65a5ba3800e0b674f348c62bfb md5 check failed (got 35890521cc6adf9b7ef4bb4689d73f10 instead of 99cf78ea0b4aeb23a2439dd886f00f8f).
Ensure the file is correctly downloaded, and update MD5S_swift