Catch KeyboardInterrupt for !commands on Windows

Building on  #6885

IPython/core/interactiveshell.py

@@ -2352,7 +2352,11 b' class InteractiveShell(SingletonConfigurable):'
                 if path is not None:
                     cmd = '"pushd %s &&"%s' % (path, cmd)
                 cmd = py3compat.unicode_to_str(cmd)
-                ec = os.system(cmd)
+                try:
+                    ec = os.system(cmd)
+                except KeyboardInterrupt:
+                    self.write_err("\nKeyboardInterrupt\n")
+                    ec = -2
         else:
             cmd = py3compat.unicode_to_str(cmd)
             # For posix the result of the subprocess.call() below is an exit

IPython/core/tests/test_interactiveshell.py

@@ -544,9 +544,9 b' class TestSystemRaw(unittest.TestCase, ExitCodeChecks):'
         cmd = u'''python -c "'åäö'"   '''
         ip.system_raw(cmd)
 
-    @mock.patch('subprocess.call')
-    def test_control_c(self, call_mock):
-        call_mock.side_effect = KeyboardInterrupt()
+    @mock.patch('subprocess.call', side_effect=KeyboardInterrupt)
+    @mock.patch('os.system', side_effect=KeyboardInterrupt)
+    def test_control_c(self, *mocks):
         try:
             self.system("sleep 1 # wont happen")
         except KeyboardInterrupt: