Description:
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When attempting to create a directory using ssh2_sftp_mkdir the command will return false if the directory has a trailing slash, however the directory will be correctly created on the remote server.

Using the package from the Ubuntu 11.04 64bit repository, version 0.11.2-1.

Reproduce code:
---------------
$connection = ssh2_connect(...);
ssh2_auth_pubkey_file(...);
$sftp = ssh2_sftp($connection);

$dir = '/tmp/has/a/slash/';
var_dump(ssh2_sftp_mkdir($sftp, $dir, 0774, true)); // Returns false but the directory is created

$dir = '/tmp/has/no/slash';
var_dump(ssh2_sftp_mkdir($sftp, rtrim($dir, '/'), 0774, true)); // returns true and the directory is created

Expected result:
----------------
The code should print

bool(true)
bool(true)

and the directories /tmp/has/no/slash and /tmp/has/a/slash should both be created.

Actual result:
--------------
The code prints

bool(false)
bool(true)

and the directories /tmp/has/no/slash and /tmp/has/a/slash are both created.