catch ConfigFileNotFound where appropriate

a few IOError catches were not updated in earlier commit 200a760b96f799fa26da295d7842ffb0bdbc3136

IPython/core/application.py

@@ -35,7 +35,7 b' import sys'
 
 from IPython.config.application import Application
 from IPython.config.configurable import Configurable
-from IPython.config.loader import Config
+from IPython.config.loader import Config, ConfigFileNotFound
 from IPython.core import release, crashhandler
 from IPython.core.profiledir import ProfileDir, ProfileDirError
 from IPython.utils.path import get_ipython_dir, get_ipython_package_dir
@@ -186,7 +186,7 b' class BaseIPythonApplication(Application):'
                 base_config,
                 path=self.config_file_paths
             )
-        except IOError:
+        except ConfigFileNotFound:
             # ignore errors loading parent
             self.log.debug("Config file %s not found", base_config)
             pass
@@ -201,7 +201,7 b' class BaseIPythonApplication(Application):'
                 self.config_file_name,
                 path=self.config_file_paths
             )
-        except IOError:
+        except ConfigFileNotFound:
             # Only warn if the default config file was NOT being used.
             if self.config_file_specified:
                 msg = self.log.warn

IPython/frontend/terminal/ipapp.py

@@ -30,7 +30,7 b' import os'
 import sys
 
 from IPython.config.loader import (
-    Config, PyFileConfigLoader
+    Config, PyFileConfigLoader, ConfigFileNotFound
 )
 from IPython.config.application import boolean_flag
 from IPython.core import release
@@ -378,7 +378,7 b' def load_default_config(ipython_dir=None):'
     cl = PyFileConfigLoader(default_config_file_name, profile_dir)
     try:
         config = cl.load_config()
-    except IOError:
+    except ConfigFileNotFound:
         # no config found
         config = Config()
     return config