Revert "librustc: Make unqualified identifier searches terminate at the nearest module scope. r=tjc"

This reverts commit a8d37af247.

src/libcore/rand.rs

@@ -15,7 +15,6 @@
 #[forbid(deprecated_pattern)];
 
 use int;
-use prelude::*;
 use str;
 use task;
 use u32;
@@ -363,8 +362,7 @@ pub fn random() -> uint {
 
 #[cfg(test)]
 pub mod tests {
-    use debug;
-    use option::{None, Option, Some};
+    use option::Option;
     use rand;
 
     #[test]