Provide guidance when called with a YouTube ID starting with a dash.

Reported at https://news.ycombinator.com/item?id=8648121

1 files changed, 5 insertions, 1 deletions

diff --git a/youtube_dl/compat.py b/youtube_dl/compat.py
index 9d33a8ec5..549206534 100644
--- a/youtube_dl/compat.py
+++ b/youtube_dl/compat.py
@@ -3,6 +3,7 @@ from __future__ import unicode_literals
 import getpass
 import optparse
 import os
+import re
 import subprocess
 import sys
 
@@ -174,7 +175,10 @@ try:
     from shlex import quote as shlex_quote
 except ImportError:  # Python < 3.3
     def shlex_quote(s):
-        return "'" + s.replace("'", "'\"'\"'") + "'"
+        if re.match(r'^[-_\w./]+$', s):
+            return s
+        else:
+            return "'" + s.replace("'", "'\"'\"'") + "'"
 
 
 def compat_ord(c):