On 10 September at a little after 17:00 PDT, I sent a message to the handling editor for my paper at the journal to which I'd submitted it on 20 February:
What is the present status of my article, and for what reason does it have that status, whatever it might be?
I've not yet received any reply.
I had waited until the 10th because, discounting the twenty days between when I received the first pair of reviews and when I sent a revision along with replies to the two reviews, that marked the sixth mensiversay.
When a paper has been held so long without a decision, the editor should not have waited to be contacted by the author(s), but should initiate contact. And, given such delay and that the author has asked for information that the editor ought to have at-hand, a query should receive a prompt reply.
Up-Date (2019:09/20): At the end of 20 September in Europe, I sent the following message both to the handling editor and to the coördinating editor:
I believe that my query of 10 days ago continues to warrant an answer, though it has not received one. I recognize that much of the unhappy history of this article at [your journal] has been outside of editorial control, but communication is surely within your power. What is the present status of my article, and for what reason does it have that status, whatever it might be?
As it seems that I should prepare to submit my article to some next journal, I have a couple of lists of journals through which to look.