Merge pull request #164 from orchardup/friendlier-build-error

Friendlier build error

fig/service.py

@@ -22,7 +22,8 @@ DOCKER_CONFIG_HINTS = {
 
 
 class BuildError(Exception):
-    pass
+    def __init__(self, service):
+        self.service = service
 
 
 class CannotBeScaledError(Exception):
@@ -308,7 +309,7 @@ class Service(object):
             sys.stdout.write(line.encode(sys.__stdout__.encoding or 'utf8'))
 
         if image_id is None:
-            raise BuildError()
+            raise BuildError(self)
 
         return image_id