Crash when compressing file with -q0

[aidanhs]

breaks-brotli.gz

Download the attached file then do

$ gunzip breaks-brotli.gz
$ RUST_BACKTRACE=1 cargo run --release --bin brotli -- -c -q0 breaks-brotli compressed
    Finished release [optimized] target(s) in 0.06s
     Running `target/release/brotli -c -q0 breaks-brotli compressed`
thread 'main' panicked at 'range start index 89173 out of range for slice of length 65536', /home/aidanhs/work/rust-brotli/src/enc/compress_fragment.rs:939:29
stack backtrace:
   0: rust_begin_unwind
             at /rustc/399ba6bb377ce02224b57c4d6e127e160fa76b34/library/std/src/panicking.rs:498:5
   1: core::panicking::panic_fmt
             at /rustc/399ba6bb377ce02224b57c4d6e127e160fa76b34/library/core/src/panicking.rs:107:14
   2: core::slice::index::slice_start_index_len_fail
             at /rustc/399ba6bb377ce02224b57c4d6e127e160fa76b34/library/core/src/slice/index.rs:35:5
   3: brotli::enc::compress_fragment::BrotliCompressFragmentFast
   4: brotli::enc::encode::BrotliEncoderCompressStreamFast
   5: brotli::main
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace