Backport PR #2399: IndentationError display

IndentationError is a subclass of SyntaxError, and they should display in a similar fashion, with the problematic line and line number shown. We were being over-specific with our type checking.

Closes  #2398.

IPython/core/interactiveshell.py

@@ -1695,7 +1695,7 b' class InteractiveShell(SingletonConfigurable):'
                 self.write_err('No traceback available to show.\n')
                 return
             
-            if etype is SyntaxError:
+            if issubclass(etype, SyntaxError):
                 # Though this won't be called by syntax errors in the input
                 # line, there may be SyntaxError cases with imported code.
                 self.showsyntaxerror(filename)
@@ -1748,7 +1748,7 b' class InteractiveShell(SingletonConfigurable):'
         """
         etype, value, last_traceback = self._get_exc_info()
 
-        if filename and etype is SyntaxError:
+        if filename and issubclass(etype, SyntaxError):
             try:
                 value.filename = filename
             except:

IPython/core/ultratb.py

@@ -563,7 +563,7 b' class ListTB(TBTools):'
             # Not sure if this can still happen in Python 2.6 and above
             list.append( str(stype) + '\n')
         else:
-            if etype is SyntaxError:
+            if issubclass(etype, SyntaxError):
                 have_filedata = True
                 #print 'filename is',filename  # dbg
                 if not value.filename: value.filename = "<string>"