Closed issue by Johnnynator on void-packages repository

https://github.com/void-linux/void-packages/issues/8590
Description: ### System

* xuname:  
  *output of ``xuname`` (part of xtools)*
* package:  
  *affected package(s) including the version*

### Expected behavior
No output to stderr

### Actual behavior

<details>

<summary>Log</summary>

```
./xbps-src -E show-build-deps kwin
=> Using `/media/SourceCode/void-packages/hostdir/binpkgs/plasma' as local repository.
/media/SourceCode/void-packages/common/xbps-src/shutils/build_dependencies.sh: line 169: unset: XBPS_BINPKG_EXISTS: cannot unset: readonly variable
/media/SourceCode/void-packages/common/xbps-src/shutils/build_dependencies.sh: line 169: unset: XBPS_BINPKG_EXISTS: cannot unset: readonly variable
/media/SourceCode/void-packages/common/xbps-src/shutils/build_dependencies.sh: line 169: unset: XBPS_BINPKG_EXISTS: cannot unset: readonly variable
/media/SourceCode/void-packages/common/xbps-src/shutils/build_dependencies.sh: line 169: unset: XBPS_BINPKG_EXISTS: cannot unset: readonly variable
/media/SourceCode/void-packages/common/xbps-src/shutils/build_dependencies.sh: line 169: unset: XBPS_BINPKG_EXISTS: cannot unset: readonly variable
/media/SourceCode/void-packages/common/xbps-src/shutils/build_dependencies.sh: line 169: unset: XBPS_BINPKG_EXISTS: cannot unset: readonly variable
/media/SourceCode/void-packages/common/xbps-src/shutils/build_dependencies.sh: line 169: unset: XBPS_BINPKG_EXISTS: cannot unset: readonly variable
/media/SourceCode/void-packages/common/xbps-src/shutils/build_dependencies.sh: line 169: unset: XBPS_BINPKG_EXISTS: cannot unset: readonly variable
/media/SourceCode/void-packages/common/xbps-src/shutils/build_dependencies.sh: line 169: unset: XBPS_BINPKG_EXISTS: cannot unset: readonly variable
/media/SourceCode/void-packages/common/xbps-src/shutils/build_dependencies.sh: line 169: unset: XBPS_BINPKG_EXISTS: cannot unset: readonly variable
/media/SourceCode/void-packages/common/xbps-src/shutils/build_dependencies.sh: line 169: unset: XBPS_BINPKG_EXISTS: cannot unset: readonly variable
/media/SourceCode/void-packages/common/xbps-src/shutils/build_dependencies.sh: line 169: unset: XBPS_BINPKG_EXISTS: cannot unset: readonly variable
/media/SourceCode/void-packages/common/xbps-src/shutils/build_dependencies.sh: line 169: unset: XBPS_BINPKG_EXISTS: cannot unset: readonly variable
/media/SourceCode/void-packages/common/xbps-src/shutils/build_dependencies.sh: line 169: unset: XBPS_BINPKG_EXISTS: cannot unset: readonly variable
/media/SourceCode/void-packages/common/xbps-src/shutils/build_dependencies.sh: line 169: unset: XBPS_BINPKG_EXISTS: cannot unset: readonly variable
/media/SourceCode/void-packages/common/xbps-src/shutils/build_dependencies.sh: line 169: unset: XBPS_BINPKG_EXISTS: cannot unset: readonly variable
/media/SourceCode/void-packages/common/xbps-src/shutils/build_dependencies.sh: line 169: unset: XBPS_BINPKG_EXISTS: cannot unset: readonly variable
/media/SourceCode/void-packages/common/xbps-src/shutils/build_dependencies.sh: line 169: unset: XBPS_BINPKG_EXISTS: cannot unset: readonly variable
/media/SourceCode/void-packages/common/xbps-src/shutils/build_dependencies.sh: line 169: unset: XBPS_BINPKG_EXISTS: cannot unset: readonly variable
breeze
....
```

</details>

### Steps to reproduce the behavior