vim-patch:9.1.0046: :drop does not re-use empty buffer (#27165)

Problem:  :drop does not re-use empty buffer
          (Rocco Mao)
Solution: Make :drop re-use an empty buffer
          (Rocco Mao)

fixes: vim/vim#13851
closes: vim/vim#13881

f96dc8d07f

Co-authored-by: Rocco Mao <dapeng.mao@qq.com>

src/nvim/arglist.c

@@ -477,7 +477,7 @@ static int do_arglist(char *str, int what, int after, bool will_edit)
 /// Redefine the argument list.
 void set_arglist(char *str)
 {
-  do_arglist(str, AL_SET, 0, false);
+  do_arglist(str, AL_SET, 0, true);
 }
 
 /// @return  true if window "win" is editing the file at the current argument

src/nvim/ex_cmds2.c

@@ -799,8 +799,7 @@ static void script_host_do_range(char *name, exarg_T *eap)
 }
 
 /// ":drop"
-/// Opens the first argument in a window.  When there are two or more arguments
-/// the argument list is redefined.
+/// Opens the first argument in a window, and the argument list is redefined.
 void ex_drop(exarg_T *eap)
 {
   bool split = false;
@@ -825,6 +824,8 @@ void ex_drop(exarg_T *eap)
     // edited in a window yet.  It's like ":tab all" but without closing
     // windows or tabs.
     ex_all(eap);
+    cmdmod.cmod_tab = 0;
+    ex_rewind(eap);
     return;
   }
 
@@ -845,6 +846,7 @@ void ex_drop(exarg_T *eap)
         buf_check_timestamp(curbuf);
         curbuf->b_p_ar = save_ar;
       }
+      ex_rewind(eap);
       return;
     }
   }