Call jl_sigatomic_begin at the end of init_julia block

This is required for using `reenable_sigint` in `pyjlwrap_call`.

See: PyCall 574

Author: tkf

julia/core.py

@@ -667,6 +667,8 @@ def __init__(self, init_julia=True, jl_init_path=None, runtime=None,
                 end
                 """)
 
+            self.api.jl_sigatomic_begin()
+
         # Currently, PyJulia assumes that `Main.PyCall` exsits.  Thus, we need
         # to import `PyCall` again here in case `init_julia=False` is passed:
         self._call(u"using PyCall")