As this was a bug (now fixed) in Bash not grep, I'm closing the grep bug report.
- bug#35681: grep's ./configure doesn't work with plain /bin... Miro Kropáček
- bug#35681: grep's ./configure doesn't work with plain... Dennis Clarke
- bug#35681: grep's ./configure doesn't work with plain... L A Walsh
- bug#35681: grep's ./configure doesn't work with p... Miro Kropáček
- bug#35681: grep's ./configure doesn't work with p... Chet Ramey
- bug#35681: grep's ./configure doesn't work with plain... Paul Eggert
