allover: numerous unused muts etc

src/libstd/ebml.rs

@@ -617,7 +617,7 @@ pub mod writer {
     priv impl Encoder {
         // used internally to emit things like the vector length and so on
         fn _emit_tagged_uint(&self, t: EbmlEncoderTag, v: uint) {
-            assert!(v <= 0xFFFF_FFFF_u);
+            assert!(v <= 0xFFFF_FFFF_u); // FIXME(#6130) assert warns on 32-bit
             self.wr_tagged_u32(t as uint, v as u32);
         }
 

src/libstd/future.rs

@@ -23,7 +23,7 @@
 
 use core::cast;
 use core::cell::Cell;
-use core::comm::{ChanOne, PortOne, oneshot, send_one};
+use core::comm::{PortOne, oneshot, send_one};
 use core::pipes::recv;
 use core::task;
 

src/libstd/sort.rs

@@ -11,7 +11,6 @@
 //! Sorting methods
 
 use core::cmp::{Eq, Ord};
-use core::util;
 use core::vec::len;
 use core::vec;
 

src/libstd/workcache.rs

@@ -17,7 +17,7 @@ use sort;
 
 use core::cell::Cell;
 use core::cmp;
-use core::comm::{ChanOne, PortOne, oneshot, send_one};
+use core::comm::{PortOne, oneshot, send_one};
 use core::either::{Either, Left, Right};
 use core::hashmap::HashMap;
 use core::io;