[database] Cleanup handling of schema version

This way beat/beat.core> doesn't depend on updating the
is_v1 flag.

beat/backend/python/database.py

@@ -251,7 +251,6 @@ class Database(object):
 
         self.errors = []
         self.data = None
-        self.is_v1 = False
 
         # if the user has not provided a cache, still use one for performance
         dataformat_cache = dataformat_cache if dataformat_cache is not None else {}
@@ -306,17 +305,14 @@ class Database(object):
         self.code_path = self.storage.code.path
         self.code = self.storage.code.load()
 
-        schema_version = int(self.data.get("schema_version", 1))
-
-        if schema_version == 1:
-            self.is_v1 = True
+        if self.schema_version == 1:
             self._load_v1(dataformat_cache)
-        elif schema_version == 2:
+        elif self.schema_version == 2:
             self._load_v2(dataformat_cache)
         else:
             raise RuntimeError(
                 "Invalid schema version {schema_version}".format(
-                    schema_version=schema_version
+                    schema_version=self.schema_version
                 )
             )
 
@@ -405,7 +401,7 @@ class Database(object):
     def sets(self, protocol):
         """The declaration of a specific set in the database protocol"""
 
-        if self.is_v1:
+        if self.schema_version == 1:
             data = self.protocol(protocol)["sets"]
         else:
             protocol = self.protocol(protocol)
@@ -426,7 +422,7 @@ class Database(object):
     def set_names(self, protocol):
         """The names of sets in a given protocol for this database"""
 
-        if self.is_v1:
+        if self.schema_version == 1:
             data = self.protocol(protocol)["sets"]
         else:
             protocol = self.protocol(protocol)
@@ -451,7 +447,7 @@ class Database(object):
 
         """
 
-        if self.is_v1:
+        if self.schema_version == 1:
             view_definition = self.set(protocol_name, set_name)
         else:
             protocol = self.protocol(protocol_name)
@@ -599,7 +595,7 @@ class Database(object):
         for k in self.dataformats.values():
             k.export(prefix)
 
-        if not self.is_v1:
+        if self.schema_version != 1:
             for protocol in self.protocols.values():
                 protocol_template = ProtocolTemplate(self.prefix, protocol["template"])
                 protocol_template.export(prefix)