Switch scripts cell magic default to raise if error happens.

Close  #11198

docs/source/whatsnew/pr/bash_raise_default.rst

@@ -0,0 +1,4 b''
+The ``%%script`` (as well as ``%%bash``, ``ruby``... ) cell magic no raise by
+default if the return code of the given code is non-zero (this halting execution
+of further cells in a notebook). The behavior can be disable by passing the
+``--no-raise-error`` flag.

IPython/core/magics/script.py

@@ -55,7 +55,7 b' def script_args(f):'
             """
         ),
         magic_arguments.argument(
-            '--raise-error', action="store_true",
+            '--no-raise-error', action="store_false", dest='raise_error',
             help="""Whether you should raise an error message in addition to 
             a stream on stderr if you get a nonzero exit code.
             """