We cannot compare against origin/main branch because we build from sdist, not git.

--- filelock-4.2.9/tox.toml.orig
+++ filelock-4.2.9/tox.toml
@@ -40,14 +40,6 @@
     ], extend = true },
     "tests",
   ],
-  { replace = "posargs", default = [
-    [
-      "diff-cover",
-      "--compare-branch",
-      { replace = "env", name = "DIFF_AGAINST", default = "origin/main" },
-      "{env_tmp_dir}{/}coverage.xml",
-    ],
-  ], extend = true },
 ]
 
 [env_pkg_base]
--- filelock-4.2.9/pyproject.toml.orig
+++ filelock-4.2.9/pyproject.toml
@@ -55,7 +55,6 @@
 ]
 test = [
   "covdefaults>=2.3",
-  "diff-cover>=10.2",
   "pytest>=9.0.3",
   "pytest-asyncio>=1.3",
   "pytest-cov>=7.1",