maven_jar: Handle SNAPSHOT artifact correcly

Change-Id: I863f25f77a8905b8f70d6b71439a0395d1904d03
diff --git a/maven_jar.bucklet b/maven_jar.bucklet
index bd68184..84812b7 100644
--- a/maven_jar.bucklet
+++ b/maven_jar.bucklet
@@ -67,7 +67,7 @@
     raise NameError('expected id="groupId:artifactId:version"')
   group, artifact, version = parts
 
-  if 'SNAPSHOT' in version:
+  if 'SNAPSHOT' in version and repository.startswith(GERRIT):
     file_version = version.replace('-SNAPSHOT', '')
     version = version.split('-SNAPSHOT')[0] + '-SNAPSHOT'
   else: