Description:
------------
This bug occurs in version 1.2.3.

The function oauth_provider_get_current_uri in provider.c returns an incorrect 
uri when the $_SERVER['HTTP'] variable is set, but empty.  It interprets this to 
mean that the protocol should be https.

The PHP documentation at http://php.net/manual/en/reserved.variables.server.php 
states that $_SERVER['HTTPS'] is "Set to a non-empty value if the script was 
queried through the HTTPS protocol."

This implies (although not unambiguously) that if $_SERVER['HTTPS'] set, but 
empty, the protocol should be http.

This error occurs for me when I am using nginx and I have the directive:
fastcgi_param HTTPS $https;

The result is that the calculated signature does not match the signature that I 
send.  OAuthProvider::reportProblem() shows that the URI is using the https 
protocol.

The error could be fixed in provider.c (rev 327831) line 438 by checking whether 
the https variable is empty.