First of all, this isn't really SourceTree's fault, but SourceTree could handle it better.

When cloning a repo like https://github.com/textmate/ruby.tmbundle which contains files with names like "Snippets/Hash.new

(Has).plist" (yes, that's a file name), SourceTree crashes. These file names are not valid in Windows. Using git directly just issues an error for those paticular files but SourceTree does not know how to handle them.