patch 8.2.4711: when 'insermode' is set :edit from <Cmd> mapping misbehaves

Problem:    When 'insermode' is set :edit from <Cmd> mapping misbehaves.
Solution:   Don't set "need_start_insertmode" when already in Insert mode.
            (closes #10116)

src/ex_cmds.c

@@ -3182,7 +3182,7 @@ do_ecmd(
 	redraw_curbuf_later(NOT_VALID);	// redraw this buffer later
     }
 
-    if (p_im)
+    if (p_im && (State & INSERT) == 0)
 	need_start_insertmode = TRUE;
 
 #ifdef FEAT_AUTOCHDIR

src/testdir/test_edit.vim

@@ -1840,6 +1840,29 @@ func Test_edit_file_no_read_perm()
   call delete('Xfile')
 endfunc
 
+" Using :edit without leaving 'insertmode' should not cause Insert mode to be
+" re-entered immediately after <C-L>
+func Test_edit_insertmode_ex_edit()
+  CheckRunVimInTerminal
+
+  let lines =<< trim END
+    set insertmode noruler
+    inoremap <C-B> <Cmd>edit Xfoo<CR>
+  END
+  call writefile(lines, 'Xtest_edit_insertmode_ex_edit')
+
+  let buf = RunVimInTerminal('-S Xtest_edit_insertmode_ex_edit', #{rows: 6})
+  call TermWait(buf, 50)
+  call assert_match('^-- INSERT --\s*$', term_getline(buf, 6))
+  call term_sendkeys(buf, "\<C-B>\<C-L>")
+  call TermWait(buf, 50)
+  call assert_notmatch('^-- INSERT --\s*$', term_getline(buf, 6))
+
+  " clean up
+  call StopVimInTerminal(buf)
+  call delete('Xtest_edit_insertmode_ex_edit')
+endfunc
+
 " Pressing escape in 'insertmode' should beep
 func Test_edit_insertmode_esc_beeps()
   new

src/version.c

@@ -746,6 +746,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    4711,
 /**/
     4710,
 /**/