We need to clarify a few terms as there are different levels of "pre-screening".
In most cases, the point of these screenings is to evaluate audience reaction to film elements, characters etc to ensure commericial success in their target audience so they CAN be edited into shape.
Making money is the primary goal, and the simplest method to do that is to give audiences what they want but you can throw in a few surprises.
So, from Wikipedia
For early edits of a film, informal test screenings are shown to small target audiences to judge if a film will require editing, reshooting or rewriting. At this stage the film may be incomplete, with missing or unfinished special effects shots or sound effects, or dialogue not yet rerecorded. Audience responses are usually recorded informally. Test audiences may be required not to discuss the film. A film may go through several test screenings.
Focus group screening
Focus group screenings are formal test screenings of a film with very detailed documentation of audience responses. Target audience members answer survey questionnaires and are usually interviewed, sometimes on video....Their opinion may be recorded by pressing buttons during screening to indicate approval or disapproval....Focus group screenings are expensive to run due to the equipment required and large amount of data recorded, so are performed less frequently than informal test screenings.
Critic (or "press") screenings are held for national and major market critics well in advance of print and television production-cycle deadlines, and are usually by invitation only. This step may be omitted if a studio anticipates negative critical reviews, or if a film is still being edited until immediately before release.
Public preview screenings can occur at boutique theaters (which may not be scheduled as a release theater). These may serve as final test screenings used to adjust marketing strategy (radio & TV promotion, etc.) or the film itself. Complimentary tickets, sometimes limited in number, are frequently provided to local media for contests or giveaways. Viewers may be recruited and "prequalified" with a series of questions to determine if they fit the film's target audience.
A sneak preview is an unannounced film screening before formal release, generally with the usual charge for admission. Sneak previews were created in the 1930s to help determine "success and failure factors" of a film, while modern sneak previews provide additional publicity and word-of-mouth exposure for the movie. A sneak preview of a film with bad (or no) prior publicity may be quite poorly received;
Since the point of most of these IS to shape the final film it would be unusual to release a changed "pre-screened" film in it's original form in the hopes that the target audience might like it anyway.
If we limit ourselves to the final stages (Preview Screenings/Sneak Previews) which is the last opportunity to withdraw the film for changes then I think this is the area to concentrate on.
As for examples,
Wikipedia specifically mentions...
A by-invitation sneak preview of Francis Ford Coppola's Apocalypse Now was dismissed by attendees as "boring," though it went on to win the Cannes Palme d'Or and a nomination for the Academy Award for Best Picture.
Blade Runner had preview screenings of the Workprint version in 1982 which led to some final changes. Of course, there are now 7 or 8 different versions of the movie of which the 2007 Final Cut a 25th anniversary digitally remastered version, is the only one on which [Ridley] Scott had complete artistic freedom and was shown in selected theaters and subsequently released on DVD, HD DVD, and Blu-ray