Cross-build of rust 1.91.0 for armv6-unknown-netbsd-eabihf fails with "found possibly newer version of crate"

Summary

While the cross-build on NetBSD/amd64 10.1 for armv7-unknown-netbsd-eabihf succeeded after applying the workaround from issue #148450 succeded, the build for armv6-unknown-netbsd-eabihf fails with a rather obtuse and new to me error message.

Command used

python3.12 ./x.py dist -j 40

Expected behaviour

I expected the build to succeed without any error message

Actual behaviour

The build failed with

   Compiling potential_utf v0.1.3
   Compiling gix-prompt v0.11.1
   Compiling gix-hash v0.19.0
   Compiling gix-fs v0.16.1
   Compiling gix-glob v0.21.0
error[E0460]: found possibly newer version of crate `bstr` which `gix_config_value` depends on
  --> /usr/pkgsrc/wip/rust191/work/rustc-1.91.0-src/vendor/gix-prompt-0.11.1/src/types.rs:72:37
   |
72 |                     .and_then(|val| gix_config_value::Boolean::try_from(val).ok())
   |                                     ^^^^^^^^^^^^^^^^
   |
   = note: perhaps that crate needs to be recompiled?
   = note: the following crate versions were found:
           crate `bstr`: /usr/pkgsrc/wip/rust191/work/rustc-1.91.0-src/build/x86_64-unknown-netbsd/stage1/lib/rustlib/armv6-unknown-netbsd-eabihf/lib/libbstr-8d7eb7ea61c08201.rmeta
           crate `gix_config_value`: /usr/pkgsrc/wip/rust191/work/rustc-1.91.0-src/build/x86_64-unknown-netbsd/stage2-tools/armv6-unknown-netbsd-eabihf/release/deps/libgix_config_value-087ad63e7ac3453f.rmeta

error[E0460]: found possibly newer version of crate `bstr` which `gix_command` depends on
  --> /usr/pkgsrc/wip/rust191/work/rustc-1.91.0-src/vendor/gix-prompt-0.11.1/src/lib.rs:30:15
   |
30 |         match gix_command::prepare(askpass).arg(prompt).spawn() {
   |               ^^^^^^^^^^^
   |
   = note: perhaps that crate needs to be recompiled?
   = note: the following crate versions were found:
           crate `bstr`: /usr/pkgsrc/wip/rust191/work/rustc-1.91.0-src/build/x86_64-unknown-netbsd/stage1/lib/rustlib/armv6-unknown-netbsd-eabihf/lib/libbstr-8d7eb7ea61c08201.rmeta
           crate `gix_command`: /usr/pkgsrc/wip/rust191/work/rustc-1.91.0-src/build/x86_64-unknown-netbsd/stage2-tools/armv6-unknown-netbsd-eabihf/release/deps/libgix_command-1160e776be7c60d6.rmeta

   Compiling icu_collections v2.0.0
   Compiling icu_locale_core v2.0.0
For more information about this error, try `rustc --explain E0460`.
error: could not compile `gix-prompt` (lib) due to 2 previous errors
warning: build failed, waiting for other jobs to finish...
Build completed unsuccessfully in 1:27:38

Why this happens for armv6hf and not for armv7hf is beyond me.

I'm looking for hints for what to look for in this case.

Bootstrap configuration (bootstrap.toml)

(empty here)

Humm, I started a build for another target architecture. The bootstrap.toml is similar to what's in #148450, except with armv6 instead of armv7.

Operating system

Host: NetBSD/amd64 10.1

HEAD

castor: {73} echo `cat work/rustc-1.91.0-src/git-commit-hash `
f8297e351a40c1439a467bbbb6879088047f50b3
castor: {74} 

Basically 1.91.0 from the release tarball.

Additional context

Start with the reported python3.12 ./x.py dist -j 40 cross-build and the empty bootstrap.toml, then compare the armv6 configuration with the armv7 workaround from issue #148450. Trace the stage1 and stage2-tools artifacts named in the E0460 output, especially bstr, gix_config_value, and gix_command; done means the armv6-unknown-netbsd-eabihf build completes without the dependency-version errors.