Strange race condition with %attach

Frequently, if I try to %attach a .pyx or .spyx file in the console, most of the time I just get something like:
sage: %attach foo.spyx
Compiling ./foo.spyx...
---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-4-263e7c85293a> in <module>()
----> 1 get_ipython().magic(u'attach foo.spyx')

/opt/sagemath-8.4/local/lib/python2.7/site-packages/IPython/core/interactiveshell.pyc in magic(self, arg_s)
   2158         magic_name, _, magic_arg_s = arg_s.partition(' ')
   2159         magic_name = magic_name.lstrip(prefilter.ESC_MAGIC)
-> 2160         return self.run_line_magic(magic_name, magic_arg_s)
   2161
   2162     #-------------------------------------------------------------------------

/opt/sagemath-8.4/local/lib/python2.7/site-packages/IPython/core/interactiveshell.pyc in run_line_magic(self, magic_name, line)
   2079                 kwargs['local_ns'] = sys._getframe(stack_depth).f_locals
   2080             with self.builtin_trap:
-> 2081                 result = fn(*args,**kwargs)
   2082             return result
   2083

<decorator-gen-115> in attach(self, s)

/opt/sagemath-8.4/local/lib/python2.7/site-packages/IPython/core/magic.pyc in <lambda>(f, *a, **k)
    186     # but it's overkill for just that one bit of state.
    187     def magic_deco(arg):
--> 188         call = lambda f, *a, **k: f(*a, **k)
    189
    190         if callable(arg):

/opt/sagemath-8.4/local/lib/python2.7/site-packages/sage/repl/ipython_extension.pyc in attach(self, s)
    156             sage: shell.quit()
    157         """
--> 158         return self.shell.ex(load_wrap(s, attach=True))
    159
    160     @line_magic

/opt/sagemath-8.4/local/lib/python2.7/site-packages/IPython/core/interactiveshell.pyc in ex(self, cmd)
   2421         """Execute a normal python statement in user namespace."""
   2422         with self.builtin_trap:
-> 2423             exec(cmd, self.user_global_ns, self.user_ns)
   2424
   2425     def ev(self, expr):

<string> in <module>()

/opt/sagemath-8.4/local/lib/python2.7/site-packages/sage/repl/load.pyc in load(filename, globals, attach)
    265         if attach:
    266             add_attached_file(fpath)
--> 267         exec(load_cython(fpath), globals)
    268     elif ext == '.f' or ext == '.f90':
    269         from sage.misc.inline_fortran import fortran

/opt/sagemath-8.4/local/lib/python2.7/site-packages/sage/repl/load.pyc in load_cython(name)
     65     """
     66     from sage.misc.cython import cython
---> 67     mod, dir = cython(name, compile_message=True, use_cache=True)
     68     import sys
     69     sys.path.append(dir)

/opt/sagemath-8.4/local/lib/python2.7/site-packages/sage/misc/cython.pyc in cython(filename, verbose, compile_message, use_cache, create_local_c_file, annotate, sage_namespace, create_local_so_file)
    619                         quiet=(verbose <= 0),
    620                         errors_to_stderr=False,
--> 621                         use_listing_file=True)
    622             finally:
    623                 # Read the "listing file" which is the file containing

/opt/sagemath-8.4/local/lib/python2.7/site-packages/Cython/Build/Dependencies.pyc in cythonize(module_list, exclude, nthreads, aliases, quiet, force, language, exclude_failures, **options)
    895         exclude_failures=exclude_failures,
    896         language=language,
--> 897         aliases=aliases)
    898     deps = create_dependency_tree(ctx, quiet=quiet)
    899     build_dir = getattr(options, 'build_dir', None)

/opt/sagemath-8.4/local/lib/python2.7/site-packages/Cython/Build/Dependencies.pyc in create_extension_list(patterns, exclude, ctx, aliases, quiet, language, exclude_failures)
    775             raise TypeError(msg)
    776
--> 777         for file in nonempty(sorted(extended_iglob(filepattern)), "'%s' doesn't match any files" % filepattern):
    778             if os.path.abspath(file) in to_exclude:
    779                 continue

/opt/sagemath-8.4/local/lib/python2.7/site-packages/Cython/Build/Dependencies.pyc in nonempty(it, error_msg)
    100         yield value
    101     if empty:
--> 102         raise ValueError(error_msg)
    103
    104

ValueError: '/home/sage/.sage/temp/NAVI-Brick/20396/spyx/_home_sage_foo_spyx/_home_sage_foo_spyx_3.pyx' doesn't match any files
But then every now and then it "just works" as expected. So I suspect there is some kind of race condition happening here: temporary files being cleaned up too quickly or something like that. I'm not exactly sure though.
sagemath / sage-windows

Strange race condition with %attach #27
