Backport PR #2169: ipdb: pdef, pdoc, pinfo magics all broken

```
In[1]: dg.meshes.square.qmesh(2)
...
IndexError: index (48) out of range (0<=index<47) in dimension 0

In [2]: debug
...
ipdb> pinfo jx
...
/usr/lib/python2.7/dist-packages/IPython/core/debugger.pyc in do_pinfo(self, arg)
    490         namespaces = [('Locals', self.curframe.f_locals),
    491                       ('Globals', self.curframe.f_globals)]
--> 492         self.shell.magic_pinfo("pinfo %s" % arg, namespaces=namespaces)
    493
    494     def checkline(self, filename, lineno):

AttributeError: 'TerminalInteractiveShell' object has no attribute 'magic_pinfo'
```

IPython/core/debugger.py

@@ -477,19 +477,20 b' class Pdb(OldPdb):'
         """The debugger interface to magic_pdef"""
         namespaces = [('Locals', self.curframe.f_locals),
                       ('Globals', self.curframe.f_globals)]
-        self.shell.magic_pdef(arg, namespaces=namespaces)
+        self.shell.find_line_magic('pdef')(arg, namespaces=namespaces)
 
     def do_pdoc(self, arg):
         """The debugger interface to magic_pdoc"""
         namespaces = [('Locals', self.curframe.f_locals),
                       ('Globals', self.curframe.f_globals)]
-        self.shell.magic_pdoc(arg, namespaces=namespaces)
+        self.shell.find_line_magic('pdoc')(arg, namespaces=namespaces)
 
     def do_pinfo(self, arg):
         """The debugger equivalant of ?obj"""
         namespaces = [('Locals', self.curframe.f_locals),
                       ('Globals', self.curframe.f_globals)]
-        self.shell.magic_pinfo("pinfo %s" % arg, namespaces=namespaces)
+        self.shell.find_line_magic('pinfo')("pinfo %s" % arg,
+                                            namespaces=namespaces)
 
     def checkline(self, filename, lineno):
         """Check whether specified line seems to be executable.

IPython/core/interactiveshell.py

@@ -1478,7 +1478,7 b' class InteractiveShell(SingletonConfigurable):'
         """Generic interface to the inspector system.
 
         This function is meant to be called by pdef, pdoc & friends."""
-        info = self._object_find(oname)
+        info = self._object_find(oname, namespaces)
         if info.found:
             pmethod = getattr(self.inspector, meth)
             formatter = format_screen if info.ismagic else None

IPython/core/tests/test_debugger.py

@@ -12,6 +12,8 b''
 # Imports
 #-----------------------------------------------------------------------------
 
+import sys
+
 # third-party
 import nose.tools as nt
 
@@ -19,6 +21,38 b' import nose.tools as nt'
 from IPython.core import debugger
 
 #-----------------------------------------------------------------------------
+# Helper classes, from CPython's Pdb test suite
+#-----------------------------------------------------------------------------
+
+class _FakeInput(object):
+    """
+    A fake input stream for pdb's interactive debugger.  Whenever a
+    line is read, print it (to simulate the user typing it), and then
+    return it.  The set of lines to return is specified in the
+    constructor; they should not have trailing newlines.
+    """
+    def __init__(self, lines):
+        self.lines = iter(lines)
+
+    def readline(self):
+        line = next(self.lines)
+        print line
+        return line+'\n'
+
+class PdbTestInput(object):
+    """Context manager that makes testing Pdb in doctests easier."""
+
+    def __init__(self, input):
+        self.input = input
+
+    def __enter__(self):
+        self.real_stdin = sys.stdin
+        sys.stdin = _FakeInput(self.input)
+
+    def __exit__(self, *exc):
+        sys.stdin = self.real_stdin
+
+#-----------------------------------------------------------------------------
 # Tests
 #-----------------------------------------------------------------------------
 
@@ -33,3 +67,57 b' def test_longer_repr():'
     # in-place, since that global is used directly by the stdlib's pdb module.
     t = debugger.Tracer()
     nt.assert_equals(trepr(a), ar)
+
+def test_ipdb_magics():
+    '''Test calling some IPython magics from ipdb.
+
+    First, set up some test functions and classes which we can inspect.
+
+    >>> class ExampleClass(object):
+    ...    """Docstring for ExampleClass."""
+    ...    def __init__(self):
+    ...        """Docstring for ExampleClass.__init__"""
+    ...        pass
+    ...    def __str__(self):
+    ...        return "ExampleClass()"
+
+    >>> def example_function(x, y, z="hello"):
+    ...     """Docstring for example_function."""
+    ...     pass
+
+    Create a function which triggers ipdb.
+
+    >>> def trigger_ipdb():
+    ...    a = ExampleClass()
+    ...    debugger.Pdb().set_trace()
+
+    >>> with PdbTestInput([
+    ...    'pdef example_function',
+    ...    'pdoc ExampleClass',
+    ...    'pinfo a',
+    ...    'continue',
+    ... ]):
+    ...     trigger_ipdb()
+    --Return--
+    None
+    > <doctest ...>(3)trigger_ipdb()
+          1 def trigger_ipdb():
+          2    a = ExampleClass()
+    ----> 3    debugger.Pdb().set_trace()
+    <BLANKLINE>
+    ipdb> pdef example_function
+     example_function(x, y, z='hello')
+     ipdb> pdoc ExampleClass
+    Class Docstring:
+        Docstring for ExampleClass.
+    Constructor Docstring:
+        Docstring for ExampleClass.__init__
+    ipdb> pinfo a
+    Type:       ExampleClass
+    String Form:ExampleClass()
+    Namespace:  Locals
+    File:       ...
+    Docstring:  Docstring for ExampleClass.
+    Constructor Docstring:Docstring for ExampleClass.__init__
+    ipdb> continue
+    '''