AUR update: Files checksums are wrong

Hi, I updated an AUR package and got checksum wrong error. I found out that this was because pamac did not re-download the files of the package. It used the files which were already downloaded from it's build cache directory. I deleted the build cache directory of pamac and it downloaded the new files and worked again.

So pamac should clear the build folder and download the new files of the package if there was an update.