Fix executor tries to create same name deployment (#1082)

The root cause of the issue was introduced by PR https://github.com/fission/fission/pull/1009/files .
To be short, even the CRD of environment was delete, it still takes time for executor (poolmgr) to destroy env pool. In our cases, the previous test creates an env and delete it when test finished, then the next one creates the same name env, but failed to create pool due to the deploy name conflict. So the executor selects the pod from the first created env pool. Then, executor starts to delete the env pool, and makes the pod state became Termination state. To fix this problem, a unique name of deployment will be returned after this PR to prevent the name conflict.

executor/fscache/functionServiceCache.go

@@ -175,14 +175,14 @@ func (fsc *FunctionServiceCache) GetByFunctionUID(uid types.UID) (*FuncSvc, erro
 func (fsc *FunctionServiceCache) Add(fsvc FuncSvc) (*FuncSvc, error) {
 	err, existing := fsc.byFunction.Set(crd.CacheKey(fsvc.Function), &fsvc)
 	if err != nil {
-		if existing != nil {
+		if IsNameExistError(err) {
 			f := existing.(*FuncSvc)
 			err2 := fsc.TouchByAddress(f.Address)
 			if err2 != nil {
 				return nil, err2
 			}
 			fCopy := *f
-			return &fCopy, err
+			return &fCopy, nil
 		}
 		return nil, err
 	}