float('inf') isn't available everywhere, use 1e9 instead

Author: A. Jesse Jiryu Davis

pymongo/common.py

@@ -94,8 +94,9 @@ def validate_positive_float(option, value):
  except (ValueError, TypeError):
  raise err
 
- # float('inf') doesn't work in 2.4 or 2.5 on Windows, but this does
- if not 0 < value < 1e100000:
+ # float('inf') doesn't work in 2.4 or 2.5 on Windows, so just cap floats at
+ # one billion - this is a reasonable approximation for infinity
+ if not 0 < value < 1e9:
  raise err
 
  return value