Rust and micro:bit - udiv.rs: No such file or directory

I am doing instructions from this https://github.com/droogmic/microrust/blob/d16c5af8f7bc695331a4206222ab7b1a8e892b5a/src/getting-started/02.00.FLASH.md

This is output from gdb:

$ gdb-multiarch -q target/thumbv6m-none-eabi/debug/microrust-start                                                                                            
Reading symbols from target/thumbv6m-none-eabi/debug/microrust-start...                                                                                                                                
(gdb) target remote :3333                                                                                                                                                                              
Remote debugging using :3333                                                                                                                                                                           
<<cortex_m_rt::ExceptionFrame as core::fmt::Debug>::fmt::Hex as core::fmt::Debug>::fmt (self=0x0 <<<cortex_m_rt::ExceptionFrame as core::fmt::Debug>::fmt::Hex as core::fmt::Debug>::fmt>,             
    f=0x0 <<<cortex_m_rt::ExceptionFrame as core::fmt::Debug>::fmt::Hex as core::fmt::Debug>::fmt>) at /home/roman/.cargo/registry/src/github.com-1ecc6299db9ec823/cortex-m-rt-0.6.11/src/lib.rs:452   
452                 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {                                                                                                                             
(gdb) monitor reset halt                                                                                                                                                                               
target halted due to debug-request, current mode: Thread                                                                                                                                               
xPSR: 0xc1000000 pc: 0x000006d0 msp: 0x000007c0                                                                                                                                                        
(gdb) target remote :3333                                                                                                                                                                              
A program is being debugged already.  Kill it? (y or n) y                                                                                                                                              
Remote debugging using :3333                                                                                                                                                                           
0x000006d0 in core::sync::atomic::compiler_fence () at /cargo/registry/src/github.com-1ecc6299db9ec823/compiler_builtins-0.1.18/src/int/udiv.rs:268                                                    
268     /cargo/registry/src/github.com-1ecc6299db9ec823/compiler_builtins-0.1.18/src/int/udiv.rs: No such file or directory.

And this from openocd:

$ openocd -f interface/cmsis-dap.cfg -f target/nrf51.cfg                                                                                                      
Open On-Chip Debugger 0.10.0                                                                                                                                                                           
Licensed under GNU GPL v2                                                                                                                                                                              
For bug reports, read                                                                                                                                                                                  
        http://openocd.org/doc/doxygen/bugs.html                                                                                                                                                       
Info : auto-selecting first available session transport "swd". To override use 'transport select <transport>'.                                                                                         
cortex_m reset_config sysresetreq                                                                                                                                                                      
adapter speed: 1000 kHz                                                                                                                                                                                
Info : CMSIS-DAP: SWD  Supported                                                                                                                                                                       
Info : CMSIS-DAP: Interface Initialised (SWD)                                                                                                                                                          
Info : CMSIS-DAP: FW Version = 1.10                                                                                                                                                                    
Info : SWCLK/TCK = 1 SWDIO/TMS = 1 TDI = 0 TDO = 0 nTRST = 0 nRESET = 1                                                                                                                                
Info : CMSIS-DAP: Interface ready                                                                                                                                                                      
Info : clock speed 1000 kHz                                                                                                                                                                            
Info : SWD DPIDR 0x0bb11477                                                                                                                                                                            
Info : nrf51.cpu: hardware has 4 breakpoints, 2 watchpoints                                                                                                                                            
Info : accepting 'gdb' connection on tcp/3333                                                                                                                                                          
Warn : Unknown device (HWID 0x000000d1)                                                                                                                                                                
undefined debug reason 7 - target needs reset                                                                                                                                                          
target halted due to debug-request, current mode: Thread                                                                                                                                               
xPSR: 0xc1000000 pc: 0x000006d0 msp: 0x000007c0                                                               
Info : dropped 'gdb' connection                         
Info : accepting 'gdb' connection on tcp/3333

I needed to reset it. I read about it here https://docs.rust-embedded.org/discovery/05-led-roulette/flash-it.html

I see that thumbv6m should work https://github.com/rust-lang/compiler-builtins/pull/276