Migrate pond away from failure

Just use an option, this is not used anyway.
1 files changed, 3 insertions(+), 7 deletions(-)

M src/pond.rs
M src/pond.rs +3 -7
@@ 8,8 8,6 @@ 
 use std::sync::{Arc, Condvar, Mutex};
 use std::thread;
 
-use failure::Fallible;
-
 /// The pond holds the collection of threads.
 ///
 /// All threads spawned from a pond must have the same return type.

          
@@ 163,17 161,15 @@ struct ThreadTermNotifier {
 }
 
 impl ThreadTermNotifier {
-    fn handle(&self) -> Fallible<ThreadTermHandle> {
+    fn handle(&self) -> Option<ThreadTermHandle> {
         let weak_alive = match self.alive {
             Some(ref arc) => Arc::downgrade(arc),
             // replace with proper error type
             None => {
-                return Err(failure::err_msg(
-                    "Notifier already dead, can not create handle",
-                ))
+                return None;
             }
         };
-        Ok(ThreadTermHandle {
+        Some(ThreadTermHandle {
             weak_alive,
             condv: Arc::clone(&self.condv),
             mutex: Arc::clone(&self.mutex),