gh-38807: fix race condition in Lib/trace.py

Instead of checking if a directory does not exist and thereafter
creating it, directly call `os.makedirs` with the `exist_ok` kwarg.

Author: buermarc

Lib/trace.py

@@ -258,8 +258,7 @@ def write_results(self, show_missing=True, summary=False, coverdir=None):
                 modulename = _modname(filename)
             else:
                 dir = coverdir
-                if not os.path.exists(dir):
-                    os.makedirs(dir)
+                os.makedirs(dir, exist_ok=True)
                 modulename = _fullmodname(filename)
 
             # If desired, get a list of the line numbers which represent

Misc/NEWS.d/next/Library/2023-09-22-22-17-45.gh-issue-38807.m9McRN.rst

@@ -0,0 +1,3 @@
+Fix race condition in :mod:`trace`. Instead of checking if a directory
+exists and creating it, directly call :func:`os.makedirs` with the kwarg
+`exist_ok=True`.