Remove %profile in perspective of using it in later IPython versions.

Raise an informative error message with both legacy and new behavior.

IPython/core/magics/basic.py

@@ -294,13 +294,9 b' Currently the magic system has the following functions:""",'
         prun : run code using the Python profiler
                (:meth:`~IPython.core.magics.execution.ExecutionMagics.prun`)
         """
-        warn("The `%profile` magic has been deprecated since IPython 2.0. Please use "
-             "the value of `get_ipython().profile` instead to see current profile in use.")
-        from IPython.core.application import BaseIPythonApplication
-        if BaseIPythonApplication.initialized():
-            print(BaseIPythonApplication.instance().profile)
-        else:
-            error("profile is an application-level value, but you don't appear to be in an IPython application")
+        raise DeprecationWarning("The `%profile` magic has been deprecated since IPython 2.0. "
+            "and removed in IPython 6.0. Please use the value of `get_ipython().profile` instead "
+            "to see current profile in use. Perhaps you meant to use `%prun` to profile code ?")
 
     @line_magic
     def pprint(self, parameter_s=''):

docs/source/whatsnew/development.rst

@@ -173,4 +173,9 b' development cycle marked for Milestone 6.0.'
   `reload` into the interactive namespace have been removed. You have to
   explicitly import `reload` from `IPython.lib.deepreload` to use it.
 
+- the :magic:`profile` used to print current IPython profile in use, and which
+  was deprecated in IPython 2.0 does now raise a `DeprecationWarning` error when
+  used. It is often confused with the :magic:`prun` and the deprecation remove
+  should free up the ``profile`` name in future versions.
+
 .. DO NOT EDIT THIS LINE BEFORE RELEASE. INCOMPAT INSERTION POINT.