This myth has been perpetuated by too many people. There was no rule change at the Nevada State Democratic Convention. In fact, the attempt by Sanders delegates to change the rules was rejected. Philip Bump:
Prior to the state convention, some Sanders supporters began an effort to shift the convention rules in a way that they viewed as more favorable to their candidate. One of those changes, the Las Vegas Sun reported, was a process for verifying voice votes; another took issue with the state party chairwoman, Roberta Lange, heading up the convention. Supporters at the event circulated petitions to the same end. The scene was set.
The first report from the credentials committee Saturday morning indicated that Clinton had a slight edge in delegates. Sanders fans voted against that report, per Jon Ralston, and then demanded a recount -- but this was simply a preliminary figure. As in the Iowa caucuses on Feb. 1, the final total delegates went through a process of realignment as the day progressed.
That was when the vote to approve the rules as written -- Roberta's Rules versus Robert's Rules, as some Sanders backers dubbed them -- was conducted by voice vote. The motion, seconded by a Sanders supporter, passed [. . .]
My emphasis. The ONLY attempt to change the rules was by Sanders delegates. It failed. No rules were changed at the Nevada state Democratic Convention.