Воркед

venv/Lib/site-packages/pip/_vendor/resolvelib/structs.py

@@ -117,13 +117,14 @@ class _FactoryIterableView(object):
 
     def __init__(self, factory):
         self._factory = factory
+        self._iterable = None
 
     def __repr__(self):
-        return "{}({})".format(type(self).__name__, list(self._factory()))
+        return "{}({})".format(type(self).__name__, list(self))
 
     def __bool__(self):
         try:
-            next(self._factory())
+            next(iter(self))
         except StopIteration:
             return False
         return True
@@ -131,7 +132,11 @@ class _FactoryIterableView(object):
     __nonzero__ = __bool__  # XXX: Python 2.
 
     def __iter__(self):
-        return self._factory()
+        iterable = (
+            self._factory() if self._iterable is None else self._iterable
+        )
+        self._iterable, current = itertools.tee(iterable)
+        return current
 
 
 class _SequenceIterableView(object):