gitk can inadvertently call executables in the worktree

Git for Windows is the Windows port of the revision control system Git. Prior to Git for Windows version 2.39.2, when gitk is run on Windows, it potentially runs executables from the current directory inadvertently, which can be exploited with some social engineering to trick users into running untrusted code. A patch is available in version 2.39.2. As a workaround, avoid using gitk (or Git GUI's "Visualize History" functionality) in clones of untrusted repositories.