Set max_rounds to an incredibly large number

We really don't want to raise ResolutionTooDeep yet since the metric is
not very useful. Try to avoid this until we come up with a better method
to count.

src/pip/_internal/resolution/resolvelib/resolver.py

@@ -1,5 +1,6 @@
 import functools
 import logging
+import sys
 
 from pip._vendor import six
 from pip._vendor.packaging.utils import canonicalize_name
@@ -132,7 +133,9 @@ def resolve(self, root_reqs, check_supported_wheels):
         resolver = RLResolver(provider, reporter)
 
         try:
-            self._result = resolver.resolve(requirements)
+            self._result = resolver.resolve(
+                requirements, max_rounds=sys.maxsize,
+            )
 
         except ResolutionImpossible as e:
             error = self.factory.get_installation_error(e)