• Keep assume-unchanged and other index flags on entries whose content does not change (status, reset, checkout, restore, stash pop, add).
• Split interactive rebase todo lists only on newlines, so a carriage return in a commit subject can no longer inject an instruction such as exec.
• Don't follow a symlinked leading directory in update_working_tree, which could remove a file outside the work tree.
• Make ancestor collection during upload-pack negotiation and pack generation linear rather than quadratic.
• Fold the commit message's first paragraph onto a single Subject line in format-patch, so later lines no longer end up in the mail headers.