* jn/grep-open:
t/t7811-grep-open.sh: remove broken/redundant creation of fake "less" script
t/t7811-grep-open.sh: ensure fake "less" is made executable
t/lib-pager.sh: remove unnecessary '^' from 'expr' regular expression
grep -O: allow optional argument specifying the pager (or editor)
grep: Add the option '--open-files-in-pager'
Unify code paths of threaded greps
grep: refactor grep_objects loop into its own function