Use explicit version checking to determine which package to import

_pytest/compat.py

@@ -22,16 +22,16 @@
     enum = None
 
 
-try:
-    from inspect import signature, Parameter as Parameter
-except ImportError:  # pragma: no cover
-    from funcsigs import signature as signature, Parameter as Parameter
-
-
 _PY3 = sys.version_info > (3, 0)
 _PY2 = not _PY3
 
 
+if _PY3:
+    from inspect import signature, Parameter as Parameter
+else:
+    from funcsigs import signature, Parameter as Parameter
+
+
 NoneType = type(None)
 NOTSET = object()
 
@@ -91,9 +91,9 @@ def getfuncargnames(function, startindex=None, cls=None):
     """
     Returns the names of a function's unbound arguments.
 
-    This should the names of all function arguments that:
+    This should return the names of all function arguments that:
         * Aren't bound to an instance or type as in instance or class methods.
-        * Don't have default value.
+        * Don't have default values.
         * Aren't bound with functools.partial.
         * Aren't replaced with mocks.