Remove unnecessary branch in %history

Previously, this `if...else` was meant to provide the "get whole
history" functionality of `%history`. It is now unnecessary, since
`get_range_by_str` is now able to do the same thing when given an empty
string, the same way a call to `get_range` would.

IPython/core/magics/history.py

@@ -184,14 +184,11 b' class HistoryMagics(Magics):'
             n = 10 if limit is None else limit
             hist = history_manager.get_tail(n, raw=raw, output=get_output)
         else:
-            if args.range:      # Get history by ranges
-                if args.pattern:
-                    range_pattern = "*" + " ".join(args.pattern) + "*"
-                    print_nums = True
-                hist = history_manager.get_range_by_str(" ".join(args.range),
-                                                        raw, get_output)
-            else:               # Just get history for the current session
-                hist = history_manager.get_range(raw=raw, output=get_output)
+            if args.pattern:
+                range_pattern = "*" + " ".join(args.pattern) + "*"
+                print_nums = True
+            hist = history_manager.get_range_by_str(" ".join(args.range),
+                                                    raw, get_output)
 
         # We could be displaying the entire history, so let's not try to pull
         # it into a list in memory. Anything that needs more space will just