repositioned some warnings and resolved last merge

- last merge introduced a double warning; resolved using @kain88-de's
  solution and applying it elsewhere
- test for warning for ResidueGroup.<resname> (FAILING)

package/MDAnalysis/core/groups.py

@@ -1515,14 +1515,12 @@ def __getitem__(self, item):
         #
         # u.atoms['HT1'] access, otherwise default
         if isinstance(item, string_types):
-            warnings.warn("Use of atom selection in [] operator is deprecated."
-                          "Use `select_atoms('name {}')`".format(item))
+            warnings.warn("Instant selectors AtomGroup['<name>'] "
+                          "will be removed in 1.0. "
+                          "Use `select_atoms('name <name>')`.",
+                          DeprecationWarning)
             try:
-                atom = self._get_named_atom(item)
-                warnings.warn("Instant selectors AtomGroup['<name>'] "
-                              "will be removed in 1.0",
-                              DeprecationWarning)
-                return atom
+                return self._get_named_atom(item)
             except (AttributeError, selection.SelectionError):
                 pass
         return super(AtomGroup, self).__getitem__(item)
@@ -1538,13 +1536,12 @@ def __getattr__(self, attr):
             # raise NDE(_ATTR_ERRORS[attr])
             raise NoDataError("AtomGroup has no fragments; this requires Bonds")
         elif hasattr(self.universe._topology, 'names'):
+            warnings.warn("Instant selectors AtomGroup.<name> "
+                          "will be removed in 1.0",
+                          DeprecationWarning)
             # Ugly hack to make multiple __getattr__s work
             try:
-                atom = self._get_named_atom(attr)
-                warnings.warn("Instant selectors AtomGroup.<name> "
-                              "will be removed in 1.0",
-                              DeprecationWarning)
-                return atom
+                return self._get_named_atom(attr)
             except selection.SelectionError:
                 pass
         raise AttributeError("{cls} has no attribute {attr}".format(

testsuite/MDAnalysisTests/core/test_groups.py

@@ -1004,6 +1004,10 @@ def test_AtomGroup_warn_getattr(self):
         name = self.u.atoms[0].name
         assert_warns(DeprecationWarning, lambda x: getattr(self.u.atoms, x), name)
 
+    def test_ResidueGroup_warn_getattr_resname(self):
+        name = self.u.residues[0].resname
+        assert_warns(DeprecationWarning, lambda x: getattr(self.u.residues, x), name)
+
     def test_Segment_warn_getattr_resname(self):
         name = self.u.residues[0].resname
         assert_warns(DeprecationWarning, lambda x: getattr(self.u.segments[0], x), name)