Revert PR #5388

We realised that  #5388 introduces a different problem of about the same
magnitude as the one it fixes (both are quite minor). A proper fix would
be too invasive this close to release, and after discussion, we decided
it was better to leave the same problem that has been in previous
releases.

IPython/core/displayhook.py

@@ -26,7 +26,6 b' from __future__ import print_function'
 import sys
 
 from IPython.core.formatters import _safe_get_formatter_method
-from IPython.core import inputsplitter
 from IPython.config.configurable import Configurable
 from IPython.utils import io
 from IPython.utils.py3compat import builtin_mod
@@ -101,7 +100,7 b' class DisplayHook(Configurable):'
         # do not print output if input ends in ';'
         try:
             cell = self.shell.history_manager.input_hist_parsed[self.prompt_count]
-            return inputsplitter.remove_comments(cell).rstrip().endswith(';')
+            return cell.rstrip().endswith(';')
         except IndexError:
             # some uses of ipshellembed may fail here
             return False

IPython/core/tests/test_interactiveshell.py

@@ -98,13 +98,13 b' class InteractiveShellTestCase(unittest.TestCase):'
     def test_dont_cache_with_semicolon(self):
         "Ending a line with semicolon should not cache the returned object (GH-307)"
         oldlen = len(ip.user_ns['Out'])
-        for cell in ['1;', '1; #a', '1;1;']:
+        for cell in ['1;', '1;1;']:
             ip.run_cell(cell, store_history=True)
             newlen = len(ip.user_ns['Out'])
             self.assertEqual(oldlen, newlen)
         i = 0
         #also test the default caching behavior
-        for cell in ['1', '1 #;', '1;1']:
+        for cell in ['1', '1;1']:
             ip.run_cell(cell, store_history=True)
             newlen = len(ip.user_ns['Out'])
             i += 1