Given following log snippets, their explanation, and nothing else, explain what failure, if any, occurred during build of this package.

  Snippets are in a format of [X] : [Y], where [X] is a log snippet, and [Y] is the explanation.

  Snippets are delimited with '================'.

  Drawing on information from all snippets, provide a concise explanation of the issue and recommend a solution.

  Explanation of the issue, and recommended solution, should take a handful of sentences.

  Snippets:

  [called `Result::unwrap()` on an `Err` value: Os { code: 24, kind: Uncategorized, message: "Too many open files" }]: [It contains the first instance of the Rust error that caused the unit test to fail.]

Issue: A Rust unit test failed with "too many open files" due to many threads opening file descriptors at once.
Resolution: Limit test parallelism by restricting the number of threads using the --test-threads parameter of %cargo_test.