Change default of round() to be as NumPy and warn about it.

doc/library/config.txt

@@ -585,7 +585,7 @@ import theano and print the config variable, as in:
 .. attribute:: config.warn.ignore_bug_before
 
     String value: ``'None'``, ``'all'``, ``'0.3'``, ``'0.4'``, ``'0.4.1'``, ``'0.5'``,
-    ``'0.6'``, ``'0.7'``, ``'0.8'``, ``'0.8.1'``, ``'0.8.2'``
+    ``'0.6'``, ``'0.7'``, ``'0.8'``, ``'0.8.1'``, ``'0.8.2'``, ``'0.9'``
 
     Default: ``'0.7'``
 

theano/configdefaults.py

@@ -692,7 +692,7 @@ AddConfigVar('warn.ignore_bug_before',
               "Warning for specific bugs can be configured with specific "
               "[warn] flags."),
              EnumStr('0.7', 'None', 'all', '0.3', '0.4', '0.4.1', '0.5', '0.6',
-                     '0.7', '0.8', '0.8.1', '0.8.2',
+                     '0.7', '0.8', '0.8.1', '0.8.2', '0.9',
                      allow_override=False),
              in_c_key=False)
 
@@ -796,6 +796,13 @@ AddConfigVar('warn.inc_set_subtensor1',
              BoolParam(warn_default('0.7')),
              in_c_key=False)
 
+AddConfigVar('warn.round',
+             "Round changed its default from Seed to use for randomized unit tests. "
+             "Special value 'random' means using a seed of None.",
+             BoolParam(warn_default('0.9')),
+             in_c_key=False)
+
+
 AddConfigVar(
     'compute_test_value',
     ("If 'True', Theano will run each op at graph build time, using "

theano/tensor/basic.py

@@ -2128,14 +2128,23 @@ def trunc(a):
 
 
 @constructor
-def iround(a, mode="half_away_from_zero"):
+def iround(a, mode=None):
     """cast(round(a,mode),'int64')"""
     return cast(round(a, mode), 'int64')
 
 
 @constructor
-def round(a, mode="half_away_from_zero"):
-    """round_mode(a) with mode in [half_away_from_zero, half_to_even]"""
+def round(a, mode=None):
+    """round_mode(a) with mode in [half_away_from_zero, half_to_even].
+    Default to half_to_even."""
+    if mode is None:
+        mode = "half_to_even"
+        if config.warn.round:
+            warnings.warn(
+                "theano.tensor.round() changed its default from"
+                " `half_away_from_zero` to `half_to_even` to have"
+                " the same default as NumPy. Use the Theano flag"
+                " `warn.round=False` to disable this warning.")
     if mode == "half_away_from_zero":
         return round_half_away_from_zero(a)
     elif mode == "half_to_even":

theano/tensor/var.py

@@ -711,7 +711,7 @@ class _tensor_py_operators(object):
         """See `theano.tensor.repeat`."""
         return theano.tensor.extra_ops.repeat(self, repeats, axis)
 
-    def round(self, mode="half_away_from_zero"):
+    def round(self, mode=None):
         """See `theano.tensor.round`."""
         return theano.tensor.basic.round(self, mode)