Add a new --no-last flag to :tab-focus

--no-last prevents going to the last focused tab if a new tab does not
need to be focused.

doc/help/commands.asciidoc

@@ -519,8 +519,7 @@ Show help about a command or setting.
 
 [[hint]]
 === hint
-Syntax: +:hint [*--mode* 'mode'] [*--add-history*] [*--rapid*]
-     ['group'] ['target'] ['args' ['args' ...]]+
+Syntax: +:hint [*--mode* 'mode'] [*--add-history*] [*--rapid*] ['group'] ['target'] ['args' ['args' ...]]+
 
 Start hinting.
 
@@ -770,8 +769,7 @@ Do nothing.
 
 [[open]]
 === open
-Syntax: +:open [*--related*] [*--bg*] [*--tab*] [*--window*] [*--secure*] [*--private*]
-     ['url']+
+Syntax: +:open [*--related*] [*--bg*] [*--tab*] [*--window*] [*--secure*] [*--private*] ['url']+
 
 Open a URL in the current/[count]th tab.
 
@@ -1091,9 +1089,7 @@ Load a session.
 
 [[session-save]]
 === session-save
-Syntax: +:session-save [*--current*] [*--quiet*] [*--force*] [*--only-active-window*]
-             [*--with-private*]
-             ['name']+
+Syntax: +:session-save [*--current*] [*--quiet*] [*--force*] [*--only-active-window*] [*--with-private*] ['name']+
 
 Save a session.
 
@@ -1212,7 +1208,7 @@ The tab index to close
 
 [[tab-focus]]
 === tab-focus
-Syntax: +:tab-focus ['index']+
+Syntax: +:tab-focus [*--no-last*] ['index']+
 
 Select the tab given as argument/[count].
 
@@ -1224,6 +1220,9 @@ If neither count nor index are given, it behaves like tab-next. If both are give
  last tab.
 
 
+==== optional arguments
+* +*-n*+, +*--no-last*+: Whether to avoid focusing last tab if already focused.
+
 ==== count
 The tab index to focus, starting with 1.
 

qutebrowser/browser/commands.py

@@ -1109,7 +1109,8 @@ class CommandDispatcher:
     @cmdutils.register(instance='command-dispatcher', scope='window')
     @cmdutils.argument('index', choices=['last'])
     @cmdutils.argument('count', count=True)
-    def tab_focus(self, index: typing.Union[str, int] = None, count=None):
+    def tab_focus(self, index: typing.Union[str, int] = None,
+                  count=None, no_last=False):
         """Select the tab given as argument/[count].
 
         If neither count nor index are given, it behaves like tab-next.
@@ -1121,13 +1122,14 @@ class CommandDispatcher:
                    Negative indices count from the end, such that -1 is the
                    last tab.
             count: The tab index to focus, starting with 1.
+            no_last: Whether to avoid focusing last tab if already focused.
         """
         index = count if count is not None else index
 
         if index == 'last':
             self._tab_focus_last()
             return
-        elif index == self._current_index() + 1:
+        elif not no_last and index == self._current_index() + 1:
             self._tab_focus_last(show_error=False)
             return
         elif index is None: