patch 8.1.2186: error for bad regexp even though regexp is not used

Problem:    Error for bad regexp even though regexp is not used, when writing
            a file. (Arseny Nasokin)
Solution:   Ignore regexp errors. (closes #5059)
diff --git a/src/version.c b/src/version.c
index dd957cd..65979b2 100644
--- a/src/version.c
+++ b/src/version.c
@@ -742,6 +742,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2186,
+/**/
     2185,
 /**/
     2184,