patch 8.2.3966: when using feedkeys() abbreviations may be blocked

Problem:    When using feedkeys() abbreviations may be blocked.
Solution:   Reset tb_no_abbr_cnt when running out of characters.
            (closes #9448)

src/getchar.c

@@ -3239,6 +3239,9 @@ vgetorpeek(int advance)
 		    if (pending_exmode_active)
 			exmode_active = EXMODE_NORMAL;
 
+		    // no chars to block abbreviation for
+		    typebuf.tb_no_abbr_cnt = 0;
+
 		    break;
 		}
 

src/testdir/test_feedkeys.vim

@@ -13,4 +13,14 @@ func Test_feedkeys_x_with_empty_string()
   quit!
 endfunc
 
+func Test_feedkeys_with_abbreviation()
+  new
+  inoreabbrev trigger value
+  call feedkeys("atrigger ", 'x')
+  call feedkeys("atrigger ", 'x')
+  call assert_equal('value value ', getline(1))
+  bwipe!
+  iunabbrev trigger
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab

src/version.c

@@ -749,6 +749,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    3966,
 /**/
     3965,
 /**/