attempt to subtract with overflow if signature is larger than expected

thread 'main' panicked at 'attempt to subtract with overflow', openpgp/src/packet/signature/mod.rs:609:33
stack backtrace:
   0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
   1: std::sys_common::backtrace::print
   2: std::panicking::default_hook::{{closure}}
   3: std::panicking::default_hook
   4: std::panicking::rust_panic_with_hook
   5: std::panicking::continue_panic_fmt
   6: rust_begin_unwind
   7: core::panicking::panic_fmt
   8: core::panicking::panic
   9: sequoia_openpgp::packet::signature::Signature4::verify_hash
             at openpgp/src/packet/signature/mod.rs:609
  10: sequoia_openpgp::packet::signature::Signature4::verify
             at /home/teythoon/repos/pep/sequoia/openpgp/src/packet/signature/mod.rs:681
  11: <sequoia_openpgp::parse::stream::Verifier<'a, H>>::finish_maybe
             at /home/teythoon/repos/pep/sequoia/openpgp/src/parse/stream.rs:629
  12: <sequoia_openpgp::parse::stream::Verifier<'a, H>>::from_buffered_reader
             at /home/teythoon/repos/pep/sequoia/openpgp/src/parse/stream.rs:536
  13: sequoia_openpgp::parse::stream::DetachedVerifier::from_buffered_reader
             at /home/teythoon/repos/pep/sequoia/openpgp/src/parse/stream.rs:1018
  14: sequoia_openpgp::parse::stream::DetachedVerifier::from_reader
             at /home/teythoon/repos/pep/sequoia/openpgp/src/parse/stream.rs:965
  15: sq::commands::verify
             at tool/src/commands/mod.rs:373
  16: sq::real_main
             at tool/src/sq.rs:255
  17: sq::main
             at tool/src/sq.rs:625
  18: std::rt::lang_start::{{closure}}
             at /usr/src/rustc-1.34.2/src/libstd/rt.rs:64
  19: std::panicking::try::do_call
  20: __rust_maybe_catch_panic
  21: std::rt::lang_start_internal
  22: std::rt::lang_start
             at /usr/src/rustc-1.34.2/src/libstd/rt.rs:64
  23: main
  24: __libc_start_main
  25: _start