fixed bug with date handling in risk report

zipline/finance/performance.py

@@ -133,13 +133,15 @@ class PerformanceTracker():
 
     """
 
-    def __init__(self, period_start, period_end, capital_base, trading_environment):
-
+    def __init__(self, trading_environment):
+        
+        
+        self.trading_environment     = trading_environment
         self.trading_day  = datetime.timedelta(hours = 6, minutes = 30)
         self.calendar_day = datetime.timedelta(hours = 24)
 
-        self.period_start            = period_start
-        self.period_end              = period_end
+        self.period_start            = self.trading_environment.period_start
+        self.period_end              = self.trading_environment.period_end
         self.market_open             = self.period_start
         self.market_close            = self.market_open + self.trading_day
         self.progress                = 0.0
@@ -147,8 +149,7 @@ class PerformanceTracker():
         self.day_count               = 0
         self.cumulative_capital_used = 0.0
         self.max_capital_used        = 0.0
-        self.capital_base            = capital_base
-        self.trading_environment     = trading_environment
+        self.capital_base            = self.trading_environment.capital_base
         self.returns                 = []
         self.txn_count               = 0
         self.event_count             = 0
@@ -156,14 +157,14 @@ class PerformanceTracker():
 
         self.cumulative_performance = PerformancePeriod(
             {},
-            capital_base,
-            starting_cash = capital_base
+            self.capital_base,
+            starting_cash = self.capital_base
         )
 
         self.todays_performance = PerformancePeriod(
             {},
-            capital_base,
-            starting_cash = capital_base
+            self.capital_base,
+            starting_cash = self.capital_base
         )