Test fixes and rebase conflicts, round 1

Author: alexcrichton

src/librustc_back/rpath.rs

@@ -115,7 +115,7 @@ fn path_relative_from(path: &Path, base: &Path) -> Option<PathBuf> {
 
     if path.is_absolute() != base.is_absolute() {
         if path.is_absolute() {
-            Some(PathBuf::new(path))
+            Some(PathBuf::from(path))
         } else {
             None
         }

src/libstd/env.rs

@@ -23,7 +23,7 @@ use error::Error;
 use ffi::{OsString, AsOsStr};
 use fmt;
 use io;
-use path::{self, Path, PathBuf};
+use path::{Path, PathBuf};
 use sync::atomic::{AtomicIsize, ATOMIC_ISIZE_INIT, Ordering};
 use sync::{StaticMutex, MUTEX_INIT};
 use sys::os as os_imp;