std: Fix create_dir_all for empty paths

Recent changes in path semantics meant that if none of the components in a
relative path existed as a part of a call to `create_dir_all` then the call
would fail as `create_dir("")` would be attempted and would fail with an OS
error.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/libstd/fs/mod.rs b/src/libstd/fs/mod.rs
index ac1f5993aa1..813283ed164 100644
--- a/src/libstd/fs/mod.rs
+++ b/src/libstd/fs/mod.rs
@@ -570,7 +570,7 @@ pub fn create_dir<P: AsPath + ?Sized>(path: &P) -> io::Result<()> {
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn create_dir_all<P: AsPath + ?Sized>(path: &P) -> io::Result<()> {
     let path = path.as_path();
-    if path.is_dir() { return Ok(()) }
+    if path == Path::new("") || path.is_dir() { return Ok(()) }
     if let Some(p) = path.parent() { try!(create_dir_all(p)) }
     create_dir(path)
 }