That’s a cool idea and nice way to get around the unique constraint. I was reluctant to drop and recreate the index at first but then remembered the “Script Index as… > Create to… > New Window” and it generates the fully qualified and complete t-SQL for you. Like this below, and it makes this kind of thing so easy. It’s what I really like about MS-SQL 'coz I certainly don’t like how much it costs to buy and deploy!!!
/****** Object: Index [IX_Summits] Script Date: 21/11/2017 11:04:55 ******/
CREATE UNIQUE NONCLUSTERED INDEX [IX_Summits] ON [dbo].[Summits]
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON)
However, your nifty trick is great when I need to do something in a hurry and don’t have access to MS SQL studio. It really is a nice bit of lateral thinking.