The ilasm roundtrip testing produces an assembly with the same baked-in assembly name, but named with a ".asm.dll" suffix instead of ".dll" suffix. It was noticed in #70876 that this leads to dotnet.exe, and previously also corerun.exe, executing the original assembly file instead of the roundtripped assembly file.
After eb9dd67 and 5713bea corerun.exe does execute the renamed file, so we are now testing the right thing, but we should probably change it to be more similar to R2R testing that ensures the same file name to avoid potential future problems.

cc @dotnet/jit-contrib