I haven't checked, but I think it should be as simple as updating lucet's proptest to 0.9.6.

[task 2020-04-15T16:11:17.075Z] error[E0495]: cannot infer an appropriate lifetime for lifetime parameter `'a` due to conflicting requirements
[task 2020-04-15T16:11:17.075Z]   --> /builds/worker/.cargo/registry/src/github.com-1ecc6299db9ec823/proptest-0.9.4/src/arbitrary/_core/iter.rs:47:23
[task 2020-04-15T16:11:17.075Z]    |
[task 2020-04-15T16:11:17.075Z] 47 |         base.prop_map(Iterator::cloned).boxed()
[task 2020-04-15T16:11:17.075Z]    |                       ^^^^^^^^^^^^^^^^
[task 2020-04-15T16:11:17.075Z]    |
[task 2020-04-15T16:11:17.076Z] note: first, the lifetime cannot outlive the lifetime `'a` as defined on the impl at 36:9...
[task 2020-04-15T16:11:17.076Z]   --> /builds/worker/.cargo/registry/src/github.com-1ecc6299db9ec823/proptest-0.9.4/src/arbitrary/_core/iter.rs:36:9
[task 2020-04-15T16:11:17.076Z]    |
[task 2020-04-15T16:11:17.076Z] 36 |         'a,
[task 2020-04-15T16:11:17.076Z]    |         ^^
[task 2020-04-15T16:11:17.076Z] note: ...so that the types are compatible
[task 2020-04-15T16:11:17.076Z]   --> /builds/worker/.cargo/registry/src/github.com-1ecc6299db9ec823/proptest-0.9.4/src/arbitrary/_core/iter.rs:47:23
[task 2020-04-15T16:11:17.076Z]    |
[task 2020-04-15T16:11:17.076Z] 47 |         base.prop_map(Iterator::cloned).boxed()
[task 2020-04-15T16:11:17.076Z]    |                       ^^^^^^^^^^^^^^^^
[task 2020-04-15T16:11:17.076Z]    = note: expected  `&'a T`
[task 2020-04-15T16:11:17.076Z]               found  `&T`
[task 2020-04-15T16:11:17.076Z]    = note: but, the lifetime must be valid for the static lifetime...
[task 2020-04-15T16:11:17.076Z] note: ...so that the type `strategy::map::Map<S, fn(A) -> core::iter::Cloned<A> {<A as core::iter::Iterator>::cloned::<'_, T>}>` will meet its required lifetime bounds
[task 2020-04-15T16:11:17.076Z]   --> /builds/worker/.cargo/registry/src/github.com-1ecc6299db9ec823/proptest-0.9.4/src/arbitrary/_core/iter.rs:47:41
[task 2020-04-15T16:11:17.076Z]    |
[task 2020-04-15T16:11:17.077Z] 47 |         base.prop_map(Iterator::cloned).boxed()
[task 2020-04-15T16:11:17.077Z]    |                                         ^^^^^
[task 2020-04-15T16:11:17.077Z] 
[task 2020-04-15T16:11:19.696Z] error: aborting due to previous error

Repro'd and tested that prop 0.96 fixes this.

I have made the change upstream in the fork of lucet being used. Upstream commit visible here and pulled in the changes. I don't have permission to land code in mozilla-central, so could I bother you to land this from the phab?

Sure, no problem.

https://hg.mozilla.org/mozilla-central/rev/53178eb247b2