Force complete match of metric keys in report extraction

Closes elastic#15

night_rally.py

@@ -269,7 +269,8 @@ def is_indexing_operation(op_name):
 
 
 def key_for(metric_pattern, metric_key, metric_name, op_name):
-    if re.match(metric_pattern, metric_name):
+    # force full regex match
+    if re.match("^%s$" % metric_pattern, metric_name):
         if metric_key == "median_indexing_throughput":
             if is_indexing_operation(op_name):
                 return metric_key

tests.py

@@ -13,6 +13,11 @@
 All,Merge throttle time,,0.00001,min
 All,Merge time,,0.00002,min
 All,Flush time,,0.00003,min
+All,Merge time (postings),,1.8252,min
+All,Merge time (stored fields),,0.7546166666666667,min
+All,Merge time (doc values),,1.5041166666666668,min
+All,Merge time (norms),,0.14778333333333335,min
+All,Merge time (points),,0.26083333333333336,min
 All,Median CPU usage,,44.35,%
 All,Total Young Gen GC,,0.183,s
 All,Total Old Gen GC,,0.039,s
@@ -131,6 +136,7 @@
 EXAMPLE_META_REPORT = """Name,Value
 Elasticsearch source revision,247cafe"""
 
+
 class RecordingSystemCall:
     def __init__(self, return_value):
         self.calls = []