[BUG FIX] $URANDOM_FH is closed FH if there is no /dev/urandom.
We should undef() if it can't open /dev/urandom.
Checking in changes prior to tagging of version 1.06.

Changelog diff is:

diff --git Changes Changes
index 3c3c2d9..24da7de 100644
--- Changes
+++ Changes
@@ -2,6 +2,12 @@ Revision history for Perl extension HTTP-Session2

 {{$NEXT}}

+1.06 2014-08-01T14:00:33Z
+
+    [BUG FIX]
+    - Random string generator doesn't works if /dev/urandom is not available.
+      This issue was introduced at 1.02.
+
 1.05 2014-08-01T11:20:13Z

     - Show warnings if the secret string is too short.