Make :spawn parse normally without maxsplit

doc/help/commands.asciidoc

@@ -696,7 +696,7 @@ You can use the `{url}` and `{url:pretty}` variables here which will get replace
 
 [[spawn]]
 === spawn
-Syntax: +:spawn [*--userscript*] [*--verbose*] [*--detach*] 'cmdline'+
+Syntax: +:spawn [*--userscript*] [*--verbose*] [*--detach*] 'cmdline' ['cmdline' ...]+
 
 Spawn a command in a shell.
 
@@ -715,10 +715,6 @@ Note the `{url}` and `{url:pretty}` variables might be useful here. `{url}` gets
 * +*-v*+, +*--verbose*+: Show notifications when the command started/exited.
 * +*-d*+, +*--detach*+: Whether the command should be detached from qutebrowser.
 
-==== note
-* This command does not split arguments after the last argument and handles quotes literally.
-* This command does not replace variables like +\{url\}+.
-
 [[stop]]
 === stop
 Stop loading in the current/[count]th tab.

qutebrowser/browser/commands.py

@@ -991,9 +991,8 @@ class CommandDispatcher:
         finally:
             self._tabbed_browser.setUpdatesEnabled(True)
 
-    @cmdutils.register(instance='command-dispatcher', scope='window',
-                       maxsplit=0, no_replace_variables=True)
-    def spawn(self, cmdline, userscript=False, verbose=False, detach=False):
+    @cmdutils.register(instance='command-dispatcher', scope='window')
+    def spawn(self, *cmdline, userscript=False, verbose=False, detach=False):
         """Spawn a command in a shell.
 
         Note the `{url}` and `{url:pretty}` variables might be useful here.
@@ -1012,14 +1011,7 @@ class CommandDispatcher:
             detach: Whether the command should be detached from qutebrowser.
             cmdline: The commandline to execute.
         """
-        try:
-            cmd, *args = shlex.split(cmdline)
-        except ValueError as e:
-            raise cmdexc.CommandError("Error while splitting command: "
-                                      "{}".format(e))
-
-        args = runners.replace_variables(self._win_id, args)
-
+        cmd, *args = cmdline
         log.procs.debug("Executing {} with args {}, userscript={}".format(
             cmd, args, userscript))
         if userscript: