[frontend] fork only successful builds

It can be temporary solution and may change. Problem is that we
cant fork runing builds as they are. Their state have to be changed
into pending. Also we probably should not fork importing builds at all.

frontend/coprs_frontend/coprs/logic/complex_logic.py

@@ -55,7 +55,7 @@ def fork_copr(cls, copr, user, dstname, dstgroup=None):
         builds_map = {}
         for package in copr.packages:
             fpackage = forking.fork_package(package, fcopr)
-            build = package.last_build()
+            build = package.last_build(successful=True)
             if not build:
                 continue