tools/x264_disable_mc_mul: fix nits

tools/x264_disable_mc_mul.py

@@ -11,10 +11,11 @@ def x264_disable_mc_mul(
     spec_outputroot: Path,
 ):
     spec = SPEC(spec_dir)
+    spec_env = spec.env()
 
     x264_dir = get_benchspec_dir(spec_outputroot) / "625.x264_s"
 
-    check_bench_dir(x264_dir)
+    assert check_bench_dir(x264_dir)
     x264_build = find_build(x264_dir / "build")
 
     assert x264_build.exists()
@@ -30,7 +31,7 @@ def x264_disable_mc_mul(
         f.write(mc_src)
 
     # Recompile
-    recompiled_x264_path = x264.recompile_mc(mc_path, x264_build, spec.env())
+    recompiled_x264_path = x264.recompile_mc(mc_path, x264_build, spec_env)
     assert recompiled_x264_path.exists()
     assert recompiled_x264_path.is_file()
 
@@ -40,11 +41,12 @@ def x264_disable_mc_mul(
     with Popen(
         spec.mkcmd_runcpu(
             spec_config,
-            ["x264"],
+            ["x264_s"],
             setprocgroup=True,
             workload="ref",
             output_root=spec_outputroot,
-        )
+        ),
+        env=spec_env,
     ) as process:
         process.wait()