patch 8.2.0604: :startinsert in a terminal window used later

Problem:    :startinsert in a terminal window used later.
Solution:   Ignore :startinsert in a terminal window. (closes #5952)

src/ex_docmd.c

@@ -7750,6 +7750,11 @@ ex_startinsert(exarg_T *eap)
 	    curwin->w_cursor.lnum = 1;
 	set_cursor_for_append_to_line();
     }
+#ifdef FEAT_TERMINAL
+    // Ignore this when running in an active terminal.
+    if (term_job_running(curbuf->b_term))
+	return;
+#endif
 
     // Ignore the command when already in Insert mode.  Inserting an
     // expression register that invokes a function can do this.

src/testdir/test_terminal.vim

@@ -2612,4 +2612,26 @@ func Test_term_nasty_callback()
   set hidden&
 endfunc
 
+func Test_term_and_startinsert()
+  CheckRunVimInTerminal
+  CheckUnix
+
+  let lines =<< trim EOL
+     put='some text'
+     term
+     startinsert
+  EOL
+  call writefile(lines, 'XTest_startinsert')
+  let buf = RunVimInTerminal('-S XTest_startinsert', {})
+
+  call term_sendkeys(buf, "exit\r")
+  call WaitForAssert({-> assert_equal("some text", term_getline(buf, 1))})
+  call term_sendkeys(buf, "0l")
+  call term_sendkeys(buf, "A<\<Esc>")
+  call WaitForAssert({-> assert_equal("some text<", term_getline(buf, 1))})
+
+  call StopVimInTerminal(buf)
+  call delete('XTest_startinsert')
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab

src/version.c

@@ -746,6 +746,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    604,
 /**/
     603,
 /**/