1.3.0 tests with `--features crypto-nettle` fail on debian CI (they did not fail with 1.1.0)

debian CI logs show a failure when testing the "crypto-nettle" configuration.

the test is run as:

debian cargo wrapper: running subprocess (['env', 'RUST_BACKTRACE=1', '/usr/bin/cargo', '-Zavoid-dev-deps', 'test', '--verbose', '--verbose', '-j48', '--target', 'x86_64-unknown-linux-gnu', '--all-targets', '--no-default-features', '--features', 'crypto-nettle'],) {}

and it fails only the parse::stream::test::decryptor test, with this message:

failures:

---- parse::stream::test::decryptor stdout ----
Error: Malformed Message: Malformed OpenPGP message
thread 'parse::stream::test::decryptor' panicked at 'assertion failed: `(left == right)`
  left: `1`,
 right: `0`: the test returned a termination value with a non-zero status code (1) which indicates a failure', /usr/src/rustc-1.48.0/library/test/src/lib.rs:192:5
stack backtrace:
   0: rust_begin_unwind
             at /usr/src/rustc-1.48.0/library/std/src/panicking.rs:483
   1: std::panicking::begin_panic_fmt
             at /usr/src/rustc-1.48.0/library/std/src/panicking.rs:437
   2: test::assert_test_result
             at /usr/src/rustc-1.48.0/library/test/src/lib.rs:192
   3: sequoia_openpgp::parse::stream::test::decryptor::{{closure}}
             at ./src/parse/stream.rs:3221
   4: core::ops::function::FnOnce::call_once
             at /usr/src/rustc-1.48.0/library/core/src/ops/function.rs:227
   5: core::ops::function::FnOnce::call_once
             at /usr/src/rustc-1.48.0/library/core/src/ops/function.rs:227
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.


failures:
    parse::stream::test::decryptor

test result: FAILED. 389 passed; 1 failed; 0 ignored; 0 measured; 0 filtered out

any suggestions for what i should try to fix, i'd be grateful.