Merge branch 'tr/maint-word-diff-regex-sticky' into maint

The regexp configured with diff.wordregex was incorrectly reused across files. By Thomas Rast (2) and Johannes Sixt (1) * tr/maint-word-diff-regex-sticky: diff: tweak a _copy_ of diff_options with word-diff diff: refactor the word-diff setup from builtin_diff_cmd t4034: diff.*.wordregex should not be "sticky" in --word-diff