Don't set explicit=True for :tab-clone/:view-source

Fixes #2624

CHANGELOG.asciidoc

@@ -55,6 +55,8 @@ Changed
 - The adblocker now also blocks non-GET requests (e.g. POST)
 - `:follow-selected` now also works with QtWebEngine
 - javascript: links can now be hinted
+- :view-source and :tab-clone now don't open the tab as "explicit" anymore, i.e.
+  (with the default settings) open it next to the active tab.
 
 Fixed
 ~~~~~

qutebrowser/browser/commands.py

@@ -433,7 +433,7 @@ class CommandDispatcher:
             new_tabbed_browser = self._new_tabbed_browser()
         else:
             new_tabbed_browser = self._tabbed_browser
-        newtab = new_tabbed_browser.tabopen(background=bg, explicit=True)
+        newtab = new_tabbed_browser.tabopen(background=bg)
         new_tabbed_browser = objreg.get('tabbed-browser', scope='window',
                                         window=newtab.win_id)
         idx = new_tabbed_browser.indexOf(newtab)
@@ -1380,7 +1380,7 @@ class CommandDispatcher:
             except cmdexc.CommandError as e:
                 message.error(str(e))
                 return
-            new_tab = self._tabbed_browser.tabopen(explicit=True)
+            new_tab = self._tabbed_browser.tabopen()
             new_tab.set_html(highlighted, current_url)
             new_tab.data.viewing_source = True