thread 'main' panicked at 'index out of bounds: the len is 0 but the index is 0', /checkout/src/libcore/slice/mod.rs:2
stack backtrace:
   0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
             at libstd/sys/unix/backtrace/tracing/gcc_s.rs:49
   1: std::sys_common::backtrace::print
             at libstd/sys_common/backtrace.rs:71
             at libstd/sys_common/backtrace.rs:59
   2: std::panicking::default_hook::{{closure}}
             at libstd/panicking.rs:211
   3: std::panicking::default_hook
             at libstd/panicking.rs:227
   4: std::panicking::rust_panic_with_hook
             at libstd/panicking.rs:463
   5: std::panicking::begin_panic_fmt
             at libstd/panicking.rs:350
   6: rust_begin_unwind
             at libstd/panicking.rs:328
   7: core::panicking::panic_fmt
             at libcore/panicking.rs:71
   8: core::panicking::panic_bounds_check
             at libcore/panicking.rs:58
   9: reform::poly::raw::gcd::<impl reform::poly::raw::multivar::MultivariatePolynomial<R, E>>::gcd
             at /checkout/src/libcore/slice/mod.rs:2336
             at /checkout/src/libcore/slice/mod.rs:2238
             at /checkout/src/liballoc/vec.rs:1708
             at src/poly/raw/gcd.rs:1180
  10: reform::poly::raw::gcd::<impl reform::poly::raw::multivar::MultivariatePolynomial<R, E>>::gcd_multiple
             at src/poly/raw/gcd.rs:1044
  11: reform::poly::raw::gcd::<impl reform::poly::raw::multivar::MultivariatePolynomial<R, E>>::gcd
             at src/poly/raw/gcd.rs:1218
  12: reform::poly::raw::gcd::<impl reform::poly::raw::multivar::MultivariatePolynomial<R, E>>::gcd
             at src/poly/raw/gcd.rs:1240
  13: reform::poly::raw::gcd::<impl reform::poly::raw::multivar::MultivariatePolynomial<R, E>>::gcd_multiple
             at src/poly/raw/gcd.rs:1044
  14: reform::poly::raw::gcd::<impl reform::poly::raw::multivar::MultivariatePolynomial<R, E>>::univariate_content_gcd
             at src/poly/raw/gcd.rs:1087
  15: reform::poly::raw::gcd::<impl reform::poly::raw::multivar::MultivariatePolynomial<R, E>>::gcd
             at src/poly/raw/gcd.rs:1230
  16: reform::poly::raw::gcd::<impl reform::poly::raw::multivar::MultivariatePolynomial<R, E>>::gcd_multiple
             at src/poly/raw/gcd.rs:1044
  17: reform::poly::raw::gcd::<impl reform::poly::raw::multivar::MultivariatePolynomial<R, E>>::univariate_content_gcd
             at src/poly/raw/gcd.rs:1087
  18: reform::poly::raw::gcd::<impl reform::poly::raw::multivar::MultivariatePolynomial<R, E>>::gcd
             at src/poly/raw/gcd.rs:1230
  19: reform::poly::polynomial::Polynomial::gcd
             at src/poly/polynomial.rs:300
  20: reform::normalize::merge_terms
             at src/normalize.rs:817
  21: reform::sort::split_merge_rec
             at src/sort.rs:52
             at src/sort.rs:81
...