Do not reset edition level to 0 on buffer change

Keep it as is, commit undo in current buffer, and we will commit it in
the new buffer when edition level gets back to 0.

src/context.cc

@@ -177,10 +177,8 @@ void Context::change_buffer(Buffer& buffer)
         return;
 
     if (m_edition_level > 0)
-    {
        this->buffer().commit_undo_group();
-       m_edition_level = 0;
+
-    }
     m_window.reset();
     if (has_client())
         client().change_buffer(buffer);

src/context.hh

@@ -121,13 +121,7 @@ struct ScopedEdition
         : m_context(context), m_buffer(&context.buffer())
     { m_context.begin_edition(); }
 
-    ~ScopedEdition()
+    ~ScopedEdition() { m_context.end_edition(); }
-    {
-        // If buffer changed, the edition count
-        // was reset.
-        if (m_buffer == &m_context.buffer())
-            m_context.end_edition();
-    }
 
     Context& context() const { return m_context; }
 private: