Backported two fixes from the Py2.1 tree (pre-unittest rewrite):

warsaw · warsaw · commit 5cf87aaf48b1 · 2001-06-04T19:35:04.000Z
----------------------------
revision 1.3
date: 2001/04/10 15:01:20;  author: gvanrossum;  state: Exp;  lines: +6 -0
Some other tests, when failing, don't always remove their TESTFN file.
Try to do it for them, so our mkdir() operation doesn't fail.
----------------------------
revision 1.2
date: 2001/03/02 05:46:17;  author: gvanrossum;  state: Exp;  lines: +3 -3
When catching errors from os.rmdir(), test for os.error, not IOError!
----------------------------

except I used OSError instead of os.error.
diff --git a/Lib/test/test_mailbox.py b/Lib/test/test_mailbox.py
@@ -2,6 +2,12 @@
 import os
 import test_support
 
+# cleanup the turds of some of the other tests. :(
+try:
+    os.unlink(test_support.TESTFN)
+except OSError:
+    pass
+
 # create a new maildir mailbox to work with:
 curdir = os.path.join(test_support.TESTFN, "cur")
 newdir = os.path.join(test_support.TESTFN, "new")
@@ -21,8 +27,8 @@
 
 finally:
     try: os.rmdir(newdir)
-    except IOError: pass
+    except OSError: pass
     try: os.rmdir(curdir)
-    except IOError: pass
+    except OSError: pass
     try: os.rmdir(test_support.TESTFN)
-    except IOError: pass
+    except OSError: pass
