ConvLayer, with_bias=True by default

Fix #787.

Introduces new behavior version (#508).

docs/configuration_reference/behavior_version.rst

@@ -22,6 +22,13 @@ and not listing legacy/deprecated parameters.
 Version History
 ---------------
 
+Behavior version 10 (2021-12-07)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+:class:`ConvLayer` use ``with_bias=True`` by default.
+
+See issue `#787 <https://github.com/rwth-i6/returnn/issues/787>`__.
+
 Behavior version 9 (2021-12-03)
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

returnn/tf/layers/basic.py

@@ -4319,6 +4319,7 @@ def __init__(self, filter_size, padding, strides=1, dilation_rate=1, groups=1,
     :param dict[str,str]|None filter_perm: transposes the filter (input filter as layer)
     :param LayerBase|None bias: if given, will not create an own parameter, but use this as the bias
     """
+    from returnn.util import BehaviorVersion
     padding = padding.upper()
     assert padding in ["SAME", "VALID"], "no other padding supported at the moment"
     assert "out_type" not in kwargs, "don't set out_type explicitly for this layer"
@@ -4425,7 +4426,10 @@ def __init__(self, filter_size, padding, strides=1, dilation_rate=1, groups=1,
       y = tf.reshape(y, tf.concat([extended_batch_shape, tf.shape(y)[1:]], axis=0))
     # y shape is [batch] + dynamic_dims + [n_out].
     if with_bias is NotSpecified:
-      with_bias = True if bias else False
+      if bias or BehaviorVersion.get() >= 10:
+        with_bias = True
+      else:
+        with_bias = False
     if bias:
       assert with_bias
     self.bias_layer = None

returnn/util/basic.py

@@ -209,7 +209,7 @@ class BehaviorVersion:
   The version will be set after the config is defined at __main__.init_config() or Engine.__init__()
   """
 
-  _latest_behavior_version = 9
+  _latest_behavior_version = 10
   _behavior_version = None  # type: typing.Optional[int]
 
   @classmethod