Use subprocess.DEVNULL helper.

synapse/util/versionstring.py

@@ -46,36 +46,37 @@ def get_version_string(module: ModuleType) -> str:
     version_string = module.__version__  # type: ignore[attr-defined]
 
     try:
-        with open(os.devnull, "w") as null:
-            cwd = os.path.dirname(os.path.abspath(module.__file__))
-
-            def _run_git_command(prefix: str, *params: str) -> str:
-                try:
-                    result = (
-                        subprocess.check_output(["git", *params], stderr=null, cwd=cwd)
-                        .strip()
-                        .decode("ascii")
+        cwd = os.path.dirname(os.path.abspath(module.__file__))
+
+        def _run_git_command(prefix: str, *params: str) -> str:
+            try:
+                result = (
+                    subprocess.check_output(
+                        ["git", *params], stderr=subprocess.DEVNULL, cwd=cwd
                     )
-                    return prefix + result
-                except (subprocess.CalledProcessError, FileNotFoundError):
-                    return ""
-
-            git_branch = _run_git_command("b=", "rev-parse", "--abbrev-ref", "HEAD")
-            git_tag = _run_git_command("t=", "describe", "--exact-match")
-            git_commit = _run_git_command("", "rev-parse", "--short", "HEAD")
-
-            dirty_string = "-this_is_a_dirty_checkout"
-            is_dirty = _run_git_command(
-                "", "describe", "--dirty=" + dirty_string
-            ).endswith(dirty_string)
-            git_dirty = "dirty" if is_dirty else ""
-
-            if git_branch or git_tag or git_commit or git_dirty:
-                git_version = ",".join(
-                    s for s in (git_branch, git_tag, git_commit, git_dirty) if s
+                    .strip()
+                    .decode("ascii")
                 )
-
-                version_string = f"{version_string} ({git_version})"
+                return prefix + result
+            except (subprocess.CalledProcessError, FileNotFoundError):
+                return ""
+
+        git_branch = _run_git_command("b=", "rev-parse", "--abbrev-ref", "HEAD")
+        git_tag = _run_git_command("t=", "describe", "--exact-match")
+        git_commit = _run_git_command("", "rev-parse", "--short", "HEAD")
+
+        dirty_string = "-this_is_a_dirty_checkout"
+        is_dirty = _run_git_command("", "describe", "--dirty=" + dirty_string).endswith(
+            dirty_string
+        )
+        git_dirty = "dirty" if is_dirty else ""
+
+        if git_branch or git_tag or git_commit or git_dirty:
+            git_version = ",".join(
+                s for s in (git_branch, git_tag, git_commit, git_dirty) if s
+            )
+
+            version_string = f"{version_string} ({git_version})"
     except Exception as e:
         logger.info("Failed to check for git repository: %s", e)