[Test] Add test for next-to-last double bad extension

test/functional/cases/105_mimetypes.robot

@@ -19,6 +19,10 @@ Zip Double Bad Extension
   ${result} =  Scan Message With Rspamc  ${TESTDIR}/messages/zip-doublebad.eml
   Check Rspamc  ${result}  MIME_DOUBLE_BAD_EXTENSION \\(\\d+\\.\\d+\\)\\[\\.pdf\\.exe\\]\\n  re=1
 
+Next-to-last Double Bad Extension
+  ${result} =  Scan Message With Rspamc  ${TESTDIR}/messages/next2last-doublebad.eml
+  Check Rspamc  ${result}  MIME_DOUBLE_BAD_EXTENSION \\(\\d+\\.\\d+\\)\\[\\.scr\\.xz\\]\\n  re=1
+
 Rar4
   ${result} =  Scan Message With Rspamc  ${TESTDIR}/messages/rar4.eml
   Check Rspamc  ${result}  MIME_BAD_EXTENSION \\(\\d+\\.\\d+\\)\\[exe\\]\\n  re=1

test/functional/messages/next2last-doublebad.eml

@@ -0,0 +1,9 @@
+Content-Type: multipart/mixed; boundary="--=_CDA2A73617693A02A72D9869"
+
+----=_CDA2A73617693A02A72D9869
+Content-Type: application/octet-stream; name="file.scr.xz"
+Content-Disposition: attachment; filename="file.scr.xz"
+Content-Transfer-Encoding: base64
+
+QlpoOTFBWSZTWeAw4GEAAADIAAAQQAAgACEAgrF3JFOFCQ4DDgYQ
+----=_CDA2A73617693A02A72D9869--