Declare an exceptional return value so that exceptions propagate.

gevent/_semaphore.pxd

@@ -5,15 +5,15 @@ cdef class Semaphore:
     cdef public int _dirty
 
     cpdef bint locked(self)
-    cpdef int release(self)
+    cpdef int release(self) except -1000
     cpdef rawlink(self, object callback)
     cpdef unlink(self, object callback)
-    cpdef int wait(self, object timeout=*)
-    cpdef bint acquire(self, int blocking=*, object timeout=*)
+    cpdef int wait(self, object timeout=*) except -1000
+    cpdef bint acquire(self, int blocking=*, object timeout=*) except -1000
     cpdef __enter__(self)
     cpdef __exit__(self, object t, object v, object tb)
 
 cdef class BoundedSemaphore(Semaphore):
     cdef readonly int _initial_value
 
-    cpdef int release(self)
+    cpdef int release(self) except -1000