ICE: The expected specialization failed to hold

[Stebalien]

When compiling src/test/run-pass/impl-trait/example-calendar.rs with #39022, I ran into the following ICE (travis log).

error: internal compiler error: src/librustc/traits/specialize/mod.rs:97: When translating substitutions for specialization, the expected specializaiton failed to hold
...
thread 'rustc' panicked at 'Box<Any>', src/librustc_errors/lib.rs:423
stack backtrace:
   1:      0x38c4d490413 - std::sys::imp::backtrace::tracing::imp::write::h006ed98a07af79c8
   2:      0x38c4d49ed14 - std::panicking::default_hook::{{closure}}::h29bdde758ec669fd
   3:      0x38c4d49e8bd - std::panicking::default_hook::h8ce4f57b1816201b
   4:      0x38c4d49f195 - std::panicking::rust_panic_with_hook::ha527bbf152b96a9f
   5:      0x38c46924617 - std::panicking::begin_panic::h01d55e81a4e5a829
   6:      0x38c46939dc9 - rustc_errors::Handler::bug::he9fe936d23591543
   7:      0x38c4a7e625a - rustc::session::opt_span_bug_fmt::{{closure}}::h99f1624dc46f130e
   8:      0x38c4a7e6065 - rustc::session::opt_span_bug_fmt::h31032ed16ce8405b
   9:      0x38c4a7e5cc2 - rustc::session::bug_fmt::haf155d760dc9c0d1
  10:      0x38c4a81b3c2 - rustc::traits::specialize::translate_substs::h108b7a80a0560c6b
  11:      0x38c4a803c49 - rustc::traits::project::confirm_select_candidate::h8aa9e2bf65235f75
  12:      0x38c4a801618 - rustc::traits::project::opt_normalize_projection_type::h6c608544acdaafbe
  13:      0x38c4a7fc31c - rustc::traits::project::project_and_unify_type::h4303c8774bf7296a
  14:      0x38c4a758108 - rustc::infer::InferCtxt::commit_if_ok::h7baf768a00504b52
  15:      0x38c4a7f9e8e - <rustc::traits::fulfill::FulfillProcessor<'a, 'b, 'gcx, 'tcx> as rustc_data_structures::obligation_forest::ObligationProcessor>::process_obligation::hc4df08fb32c2f015
  16:      0x38c4a692dd7 - <rustc_data_structures::obligation_forest::ObligationForest<O>>::process_obligations::h05207a7b88042398
  17:      0x38c4a7f86d7 - rustc::traits::fulfill::FulfillmentContext::select_where_possible::h6a71ef9637add14a
  18:      0x38c4b92b319 - rustc_typeck::check::FnCtxt::select_obligations_where_possible::h8441133a951b3f89
  19:      0x38c4b92c600 - rustc_typeck::check::FnCtxt::check_argument_types::h43a2217507999c34
  20:      0x38c4b92bce8 - rustc_typeck::check::FnCtxt::check_method_argument_types::he5c2672b4788e51c
  21:      0x38c4b93a6c5 - rustc_typeck::check::FnCtxt::check_expr_kind::ha4290435c9a6472f
  22:      0x38c4b937d1d - rustc_typeck::check::FnCtxt::check_expr_with_expectation_and_lvalue_pref::h1718ad876ea15e9d
  23:      0x38c4b94a5bd - rustc_typeck::check::FnCtxt::check_decl_initializer::h76279d7039c031ee
  24:      0x38c4b94a6c4 - rustc_typeck::check::FnCtxt::check_decl_local::hd78758c2b826cd55
  25:      0x38c4b94a9f6 - rustc_typeck::check::FnCtxt::check_stmt::h8392e702cb6899b0
  26:      0x38c4b94ad4e - rustc_typeck::check::FnCtxt::check_block_with_expected::h8e5f141b4696de7b
  27:      0x38c4b938187 - rustc_typeck::check::FnCtxt::check_expr_kind::ha4290435c9a6472f
  28:      0x38c4b937d1d - rustc_typeck::check::FnCtxt::check_expr_with_expectation_and_lvalue_pref::h1718ad876ea15e9d
  29:      0x38c4b91db71 - rustc_typeck::check::check_fn::h1979d8127971e8cb
  30:      0x38c4b91cb84 - rustc_typeck::check::check_bare_fn::h3ed0606ed517ee6f
  31:      0x38c4b91f741 - rustc_typeck::check::check_item_body::he9e79e65ed5d897b
  32:      0x38c4b919d4a - rustc_typeck::check::check_item_bodies::h2132a6ba61922f47
  33:      0x38c4b98bed7 - rustc_typeck::check_crate::he7efcf7e8fe91081
  34:      0x38c4d850347 - rustc_driver::driver::phase_3_run_analysis_passes::{{closure}}::hd12f5906a3bad0b1
  35:      0x38c4d7abb99 - rustc::ty::context::TyCtxt::create_and_enter::h175f09027374055c
  36:      0x38c4d82acd0 - rustc_driver::driver::compile_input::he75659f0a4c94991
  37:      0x38c4d86ff22 - rustc_driver::run_compiler::h24edcb3b397374e9
  38:      0x38c4d77465b - std::panicking::try::do_call::h91593801b844e93f
  39:      0x38c4d4a7b16 - __rust_maybe_catch_panic
  40:      0x38c4d79e202 - <F as alloc::boxed::FnBox<A>>::call_box::h3b891c67d21d918b
  41:      0x38c4d49db90 - std::sys::imp::thread::Thread::new::thread_start::h6fb015bd685b45e0
  42:      0x38c460cd453 - start_thread
  43:      0x38c4d1617de - __GI___clone
  44:                0x0 - <unknown>

[Stebalien]

Dup of #36804.