SHA1 error when using brew install

Question

More specifically, I was using homebrew to install MySQL, and I got this error:

Error: SHA1 mismatch   Expected: f218ed64ce6e7a5d3670acdd6a18e5ed95421d1f   Got: 3a57f6f44186e0dba34ef8b8fb4a9047e9e5d8a3   Archive: /Users/rdp/Library/Caches/Homebrew/cmake-2.8.7.bottle.tar.gz   (To retry an incomplete download, remove the file above.) 

Answer 1

Everything worked after I ran brew update.

Answer 2

Incase the brew update fails, try the following

cd `brew --prefix` git remote add origin https://github.com/Homebrew/homebrew git fetch origin git reset --hard origin/master