Try doctest with full exception name

tests/api_tests.txt

@@ -211,7 +211,7 @@ working set triggers a ``pkg_resources.VersionConflict`` error:
     >>> ws.find(Requirement.parse("Bar==1.0")) # doctest: +NORMALIZE_WHITESPACE
     Traceback (most recent call last):
       ...
-    VersionConflict: (Bar 0.9 (http://example.com/something),
+    pkg_resources.VersionConflict: (Bar 0.9 (http://example.com/something),
                                     Requirement.parse('Bar==1.0'))
 
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