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)
diff --git a/src/ex_docmd.c b/src/ex_docmd.c
index 5c18b0b..e2d771e 100644
--- a/src/ex_docmd.c
+++ b/src/ex_docmd.c
@@ -7750,6 +7750,11 @@
 	    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.