2:     0x55d42d3694ac - backtrace::capture::Backtrace::new::hbf014b5271d64ddb                                                                             
                        at /home/dpc/.cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.9/src/capture.rs:63                                       
   3:     0x55d42d1fde47 - grin_util::logger::send_panic_to_log::{{closure}}::h2fd826c4de6af11d                                                              
                        at util/src/logger.rs:190
   4:     0x55d42d853823 - std::panicking::rust_panic_with_hook::hcee6c3e2546f0536                                                                           
                        at libstd/panicking.rs:479
   5:     0x55d42d8533c9 - std::panicking::continue_panic_fmt::h4eabd8b3f6ed92ef                                                                             
                        at libstd/panicking.rs:390
   6:     0x55d42d8532c5 - rust_begin_unwind
                        at libstd/panicking.rs:325
   7:     0x55d42d8aea1b - core::panicking::panic_fmt::he96889401c792f2b
                        at libcore/panicking.rs:77
   8:     0x55d42d8ae9cf - core::panicking::panic_bounds_check::hd8121da93ba8d162                                                                            
                        at libcore/panicking.rs:59
   9:     0x55d42c4942dc - <usize as core::slice::SliceIndex<[T]>>::index::h174a2697209eaefd                                                                 
                        at /checkout/src/libcore/slice/mod.rs:2085
  10:     0x55d42c48bbc6 - core::slice::<impl core::ops::index::Index<I> for [T]>::index::ha9bd9698d0c84f8a                                                  
                        at /checkout/src/libcore/slice/mod.rs:1953
  11:     0x55d42c4585c2 - <alloc::vec::Vec<T> as core::ops::index::Index<I>>::index::hde444f1de14c11b9                                                      
                        at /checkout/src/liballoc/vec.rs:1714
  12:     0x55d42c4c82ea - grin_servers::grin::sync::header_sync::HeaderSync::get_locator::hfe47aaa3c8677eb8                                                 
                        at servers/src/grin/sync/header_sync.rs:193
  13:     0x55d42c4c72f7 - grin_servers::grin::sync::header_sync::HeaderSync::request_headers::h431692480453f779                                             
                        at servers/src/grin/sync/header_sync.rs:140
  14:     0x55d42c4c717b - grin_servers::grin::sync::header_sync::HeaderSync::header_sync::hca94bcde0a265f06                                                 
                        at servers/src/grin/sync/header_sync.rs:132
  15:     0x55d42c4c6c29 - grin_servers::grin::sync::header_sync::HeaderSync::check_run::hecbd8fc90a34f2a9                                                   
                        at servers/src/grin/sync/header_sync.rs:87
  16:     0x55d42c4c41d0 - grin_servers::grin::sync::syncer::SyncRunner::sync_loop::hbe5db9f98c0762bc                                                        
                        at servers/src/grin/sync/syncer.rs:148
  17:     0x55d42c501d94 - grin_servers::grin::sync::syncer::run_sync::{{closure}}::hd3b5a5588125828c                                                        
                        at servers/src/grin/sync/syncer.rs:38
  18:     0x55d42c50a9ed - std::sys_common::backtrace::__rust_begin_short_backtrace::ha047b15c565380cd                                                       
                        at /checkout/src/libstd/sys_common/backtrace.rs:136
  19:     0x55d42c4f64e0 - std::thread::Builder::spawn::{{closure}}::{{closure}}::h470019b687c8312b                                                          
                        at /checkout/src/libstd/thread/mod.rs:409

            if self.history_locators.len() > 0 && tmp[0].0 == 0 {