vim-patch:8.2.1837: using "gn" after "gN" does not work

Problem:    Using "gn" after "gN" does not work.
Solution:   Extend the other end of the Visual area. (closes vim/vim#7109)
c07b7f701f

N/A patches for version.c:

vim-patch:8.2.1834: PyEval_InitThreads() is deprecated in Python 3.9

Problem:    PyEval_InitThreads() is deprecated in Python 3.9.
Solution:   Do not call PyEval_InitThreads in Python 3.9 and later. (Ken
            Takata, closes vim/vim#7113)  Avoid warnings for functions.
efc0d94afc

src/nvim/search.c

@@ -4097,7 +4097,7 @@ abort_search:
 int
 current_search(
     long count,
-    int forward  // true for forward, false for backward
+    bool forward  // true for forward, false for backward
 )
 {
   bool old_p_ws = p_ws;
@@ -4112,6 +4112,11 @@ current_search(
   pos_T pos;                    // position after the pattern
   int result;                   // result of various function calls
 
+  // When searching forward and the cursor is at the start of the Visual
+  // area, skip the first search backward, otherwise it doesn't move.
+  const bool skip_first_backward = forward && VIsual_active
+    && lt(curwin->w_cursor, VIsual);
+
   orig_pos = pos = curwin->w_cursor;
   if (VIsual_active) {
     // Searching further will extend the match.
@@ -4129,13 +4134,20 @@ current_search(
     return FAIL;  // pattern not found
   }
 
-  /*
+  // The trick is to first search backwards and then search forward again,
-   * The trick is to first search backwards and then search forward again,
+  // so that a match at the current cursor position will be correctly
-   * so that a match at the current cursor position will be correctly
+  // captured.  When "forward" is false do it the other way around.
-   * captured.
-   */
   for (int i = 0; i < 2; i++) {
-    int dir = forward ? i : !i;
+    int dir;
+    if (forward) {
+      if (i == 0 && skip_first_backward) {
+        continue;
+      }
+      dir = i;
+    } else {
+      dir = !i;
+    }
+
     int flags = 0;
 
     if (!dir && !zero_width) {
@@ -4182,10 +4194,16 @@ current_search(
     VIsual = start_pos;
   }
 
-  // put cursor on last character of match
+  // put the cursor after the match
   curwin->w_cursor = end_pos;
   if (lt(VIsual, end_pos) && forward) {
-    dec_cursor();
+    if (skip_first_backward) {
+      // put the cursor on the start of the match
+      curwin->w_cursor = pos;
+    } else {
+      // put the cursor on last character of match
+      dec_cursor();
+    }
   } else if (VIsual_active && lt(curwin->w_cursor, VIsual) && forward) {
     curwin->w_cursor = pos;   // put the cursor on the start of the match
   }

src/nvim/testdir/test_gn.vim

@@ -169,6 +169,22 @@ func Test_gN_repeat()
   bwipe!
 endfunc
 
+func Test_gN_then_gn()
+  new
+
+  call setline(1, 'this list is a list with a list of a last.')
+  /l.st
+  normal $gNgNgnx
+  call assert_equal('last', @")
+
+  call setline(1, 'this list is a list with a lust of a last.')
+  /l.st
+  normal $gNgNgNgnx
+  call assert_equal('lust of a last', @")
+
+  bwipe!
+endfunc
+
 func Test_gn_multi_line()
   new
   call setline(1, [