* gnu/packages/crates-io.scm (rust-test-case-macros-3): New variable. (rust-test-case-macros-2): Inherit from rust-test-case-macros-3.
* gnu/packages/crates-io.scm (rust-test-case-macros-3): New variable. (rust-test-case-macros-2): Inherit from rust-test-case-macros-3.