building rustc during stage1 fails with can't find crate for core/std for stage0 rust tools

Contiuing my quest to build a pentium 3 install iso:

   Compiling thread_local v1.1.8
   Compiling tracing-log v0.2.0
   Compiling tracing v0.1.37
   Compiling tracing-subscriber v0.3.18
   Compiling llvm-bitcode-linker v0.0.1 (/srv/t2-trunk/src.rustc.240807.225931.2727/rustc-1.80.0-src/src/tools/llvm-bitcode-linker)
    Finished `release` profile [optimized] target(s) in 3.41s
Building stage2 library artifacts (x86_64-unknown-linux-gnu -> i686-t2-linux-gnu)
warning: `/srv/t2-trunk/build/default-24-svn-generic-x86-pentium3-cross-linux/TOOLCHAIN/.cargo/config` is deprecated in favor of `config.toml`
note: if you need to support cargo 1.38 or earlier, you can symlink `config` to `config.toml`
warning: flag `-Z check-cfg` has been stabilized in the 1.80 release, and is no longer necessary
  Compile-time checking of conditional (a.k.a. `-Zcheck-cfg`) is now always enabled.

    Finished `release` profile [optimized] target(s) in 0.32s
Building stage0 tool rust-installer (x86_64-unknown-linux-gnu)
warning: `/srv/t2-trunk/build/default-24-svn-generic-x86-pentium3-cross-linux/TOOLCHAIN/.cargo/config` is deprecated in favor of `config.toml`
note: if you need to support cargo 1.38 or earlier, you can symlink `config` to `config.toml`
warning: flag `-Z check-cfg` has been stabilized in the 1.80 release, and is no longer necessary
  Compile-time checking of conditional (a.k.a. `-Zcheck-cfg`) is now always enabled.

   Compiling crossbeam-utils v0.8.19
   Compiling proc-macro2 v1.0.82
   Compiling libc v0.2.155
   Compiling unicode-ident v1.0.12
   Compiling rustix v0.38.34
   Compiling utf8parse v0.2.1
   Compiling cfg-if v1.0.0
   Compiling cc v1.0.97
   Compiling pkg-config v0.3.30
   Compiling is_terminal_polyfill v1.70.0
error[E0463]: can't find crate for `core`
  |
  = note: the `x86_64-unknown-linux-gnu` target may not be installed
  = help: consider downloading the target with `rustup target add x86_64-unknown-linux-gnu`
  = help: consider building the standard library from source with `cargo build -Zbuild-std`

error[E0463]: can't find crate for `std`
  |
  = note: the `x86_64-unknown-linux-gnu` target may not be installed
  = help: consider downloading the target with `rustup target add x86_64-unknown-linux-gnu`
  = help: consider building the standard library from source with `cargo build -Zbuild-std`

For more information about this error, try `rustc --explain E0463`.
error: could not compile `is_terminal_polyfill` (lib) due to 1 previous error
warning: build failed, waiting for other jobs to finish...
error: could not compile `utf8parse` (lib) due to 1 previous error
error: could not compile `cfg-if` (lib) due to 1 previous error
Build completed unsuccessfully in 0:00:08
Due to previous errors, no 1-rustc.log file!
(Try enabling xtrace in the config to track an error inside the build system.)
--- BUILD ERROR ---
Creating file list and doing final adaptions ... 
Warning: Created vanished file outside basedir: /etc/.tmp
base #1: /srv/t2-trunk
base #2: /srv/t2-trunk/build/default-24-svn-generic-x86-pentium3-cross-linux
Searching for orphaned files ...
Found 6 files for this package.
Found 1 orphaned files for this package.
Calculating package dependencies ...
Deleting dependencies, pattern:  -e ".*: t2-src$" -e ".*: glibc$" -e ".*: gcc$" ...
Adding dependencies
Marking optional dependencies
Creating md5sum files ...
Creating package description ...
Making post-install adaptions.

ERROR-LOG.gz

I can't really figure out what could be causing this. It's only that part that fails while the rest of it builds fine.

rxrbln / t2sde

building rustc during stage1 fails with can't find crate for core/std for stage0 rust tools #177