ci: retire the busybox-w32 PR workaround for ash.exe

Until now, the workflow pulled `ash.exe` from an unmerged `busybox-w32` PR build because the `busybox.exe` shipped in the SDK was broken, and was separately also slow on account of being size-optimized. Both the correctness fix and a speed-optimized rebuild have since landed as a regular `mingw-w64-x86_64-busybox` package, so the in-flight workaround can go. I still assert a minimum installed version, because a stale SDK image could pin an older `busybox`, and I would much rather have CI fail loudly than silently run the test suite under a slow shell.

Assisted-by: Opus 4.7
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: dscho

.github/workflows/main.yml

@@ -155,20 +155,16 @@ jobs:
       env:
         GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
       run: |
-        # TEMPORARY: pull the freshly-built, heap-corruption-fixed ash.exe
-        # straight from the busybox-w32 PR build (git-for-windows/busybox-w32#15)
-        # instead of the stale copy shipped in git-sdk-64. Once that fix is
-        # released into the SDK this step reverts to the pinned download.
         run_id="$(gh run list -R git-for-windows/busybox-w32 \
-          --branch fix-quote-arg-msys2-heap-corruption \
-          --workflow build.yml --status success --limit 1 \
+          --branch main --workflow build.yml --status success --limit 1 \
           --json databaseId --jq '.[0].databaseId')" &&
         test -n "$run_id" &&
         gh run download -R git-for-windows/busybox-w32 "$run_id" \
           -n busybox -D bb &&
         test -f bb/busybox.exe &&
-        cp bb/busybox.exe /mingw64/bin/ash.exe &&
-        ash="$(cygpath -am /mingw64/bin/ash.exe)" &&
+        install -d /mingw64/libexec/busybox &&
+        cp bb/busybox.exe /mingw64/libexec/busybox/ash.exe &&
+        ash="$(cygpath -am /mingw64/libexec/busybox/ash.exe)" &&
         echo "GIT_TEST_SHELL_PATH=$ash" >>$GITHUB_ENV &&
         echo "SHELL=$ash" >>$GITHUB_ENV &&
         echo "SHELL_PATH=$ash" >>$GITHUB_ENV &&