Remove a check that would break with pinned revision using ssh protocol with a user name in the url

gclient.py

Index: gclient.py
diff --git a/gclient.py b/gclient.py
index 7595893110accb713b303b11177873f7539fce02..5757d4229559a85770e07dc9f91634515abc59ec 100644
--- a/gclient.py
+++ b/gclient.py
@@ -168,8 +168,6 @@ class DependencySettings(GClientKeywords):
     if isinstance(self._url, basestring):
       # urls are sometime incorrectly written as proto://host/path/@rev. Replace
       # it to proto://host/path@rev.
-      if self._url.count('@') > 1:
-        raise gclient_utils.Error('Invalid url "%s"' % self._url)
       self._url = self._url.replace('/@', '@')

[Peter Mayo, 2012/02/23 20:32:56]

I think the RFC precludes using slashes in the user name in a URL, so this is
OK, but it has been too long since I last read it.

[Peter Mayo, 2012/02/23 20:49:57]

1738 section 3.1 requires encoding of the @ and / within the user.  I don't see
it precluding an empty user tho.

ssh://@foo.com:2104/funky/@dean  now get mangled, but allowed.

[M-A Ruel, 2012/02/23 20:50:07]

As long as we make sure it doesn't work, it's fine. :)

[M-A Ruel, 2012/02/23 20:51:04]

The important part is that it'll fail to sync. Which is fine with me. "Silent
corruption" would annoy me but plain failure is fine.

     elif not isinstance(self._url,
         (self.FromImpl, self.FileImpl, None.__class__)):