Use a tempdir for the 'testfsoids' database.

Prevent contention when parallel tests are running under tox.

src/ZODB/tests/testfsoids.py

@@ -167,11 +167,15 @@ Clean up.
 >>> st.cleanup() # remove .fs, .index, etc
 """
 
-import re
 import doctest
-import ZODB.tests.util
+import re
+
 from zope.testing import renormalizing
 
+from .util import checker as util_checker
+from .util import setUp
+from .util import tearDown
+
 checker = renormalizing.RENormalizing([
     # Normalizing this makes diffs easier to read
     (re.compile(r'\btid 0x[0-9a-f]+\b'), 'tid 0x...'),
@@ -191,5 +195,7 @@ checker = renormalizing.RENormalizing([
 
 
 def test_suite():
-    return doctest.DocTestSuite(checker=ZODB.tests.util.checker + checker,
+    return doctest.DocTestSuite(setUp=setUp,
+                                tearDown=tearDown,
+                                checker=util_checker + checker,
                                 optionflags=doctest.REPORT_NDIFF)