patch 8.0.0681: unnamed register only contains the last deleted text

Problem:    Unnamed register only contains the last deleted text when
            appending deleted text to a register. (Wolfgang Jeltsch)
Solution:   Only set y_previous when not using y_append. (Christian Brabandt)

src/ops.c

@@ -1636,7 +1636,9 @@ shift_delete_registers()
     free_yank_all();			/* free register nine */
     for (n = 9; n > 1; --n)
 	y_regs[n] = y_regs[n - 1];
-    y_previous = y_current = &y_regs[1];
+    y_current = &y_regs[1];
+    if (!y_append)
+	y_previous = y_current;
     y_regs[1].y_array = NULL;		/* set register one to empty */
 }
 

src/testdir/test_put.vim

@@ -34,3 +34,14 @@ func Test_put_char_block2()
   bw!
   call setreg('a', a[0], a[1])
 endfunc
+
+func Test_put_lines()
+  new
+  let a = [ getreg('a'), getregtype('a') ]
+  call setline(1, ['Line 1', 'Line2', 'Line 3', ''])
+  exe 'norm! gg"add"AddG""p'
+  call assert_equal(['Line 3', '', 'Line 1', 'Line2'], getline(1,'$'))
+  " clean up
+  bw!
+  call setreg('a', a[0], a[1])
+endfunc

src/version.c

@@ -764,6 +764,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    681,
 /**/
     680,
 /**/