Handle the Balanced API more saferly during payday

This makes us more robust in the face of failures communicating with the
Balanced API. Now we've got a blanket try/except around the parts where
we talk to Balanced, so we will never totally crash because of a
mishandling of some sort. The ach_credit side is not as well-factored
as the charge_on_balanced side, and is not tested as a result. This
commit nonetheless attempts to implement the same error handling on both
sides.

gittip/billing/payday.py

@@ -18,6 +18,7 @@
 """
 from __future__ import unicode_literals
 
+import sys
 from decimal import Decimal, ROUND_UP
 
 import balanced
@@ -633,10 +634,14 @@ def ach_credit(self, ts_start, participant, tips, total):
                                   .credit(amount=cents,
                                           description=participant.username)
 
-            error = ""
             log(msg + "succeeded.")
+            error = ""
         except balanced.exc.HTTPError as err:
-            error = err.message
+            error = err.message.message
+        except:
+            error = repr(sys.exc_info()[1])
+
+        if error:
             log(msg + "failed: %s" % error)
 
         self.record_credit(credit_amount, fee, error, participant.username)
@@ -660,6 +665,10 @@ def charge_on_balanced(self, username, balanced_customer_href, amount):
             error = ""
         except balanced.exc.HTTPError as err:
             error = err.message.message
+        except:
+            error = repr(sys.exc_info()[1])
+
+        if error:
             log(msg + "failed: %s" % error)
 
         return charge_amount, fee, error

tests/test_billing_payday.py

@@ -262,15 +262,15 @@ def test_charge_on_balanced_handles_MultipleFoundError(self):
                                                , self.balanced_customer_href
                                                , D('10.00')
                                                 )
-        assert actual == (D('10.61'), D('0.61'), 'MultipleFoundError')
+        assert actual == (D('10.61'), D('0.61'), 'MultipleResultsFound()')
 
     def test_charge_on_balanced_handles_NotFoundError(self):
         customer_with_no_card = unicode(balanced.Customer().save().href)
         actual = self.payday.charge_on_balanced( 'whatever username'
                                                , customer_with_no_card
                                                , D('10.00')
                                                 )
-        assert actual == (D('10.61'), D('0.61'), 'NotFoundError')
+        assert actual == (D('10.61'), D('0.61'), 'NoResultFound()')
 
 
 class TestBillingCharges(PaydayHarness):