Merge branch 'jc/diff-from-contents-fix' into maint-2.51

The code to squelch output from "git diff -w --name-status" etc. for paths that "git diff -w -p" would have stayed silent leaked output from dry-run patch generation, which has been corrected. * jc/diff-from-contents-fix: diff: make sure the other caller of diff_flush_patch_quietly() is silent