It seems very likely that preventing spoilers was also part of the reason that the release date for Avengers: Infinity War was moved up.
Originally, the film was going to release on May 4, but that date has been changed to April 27.
Infinity War is seeing a near global release between April 25 and 27, meaning that the potential for spoilers before everybody at least has a chance to see it are greatly reduced.
Considering that the movie was also going to be released in many other territories that weekend already, shifting the date reduces the period where the movie can be seen in Europe and spoiled here.