How to fix a broken git after upgrading to macOS Sierra

Yesterday I’ve upgraded my Mac to the new macOS Sierra. Everything worked great except that my git installation was broken afterwards. The error message I got when using git on the command line was the following:

xcrun: error: invalid active developer path (/Library/Developer/CommandLineTools), missing xcrun at: /Library/Developer/CommandLineTools/usr/bin/xcrun

Gladly there is an easy solution to this problem. Just enter xcode-select --install into your terminal and (re)install the CommandLineTools.