PR tests: add excerpts from original bug reports, for clarity. * tests/pr2.test: Ditto. * tests/pr9.test: Likewise. * tests/pr72.test: Likewise. * tests/pr87.test: Likewise. * tests/pr211.test: Likewise. * tests/pr220.test: Likewise. * tests/pr224.test: Likewise. * tests/pr229.test: Likewise. * tests/pr243.test: Likewise. * tests/pr266.test: Likewise. * tests/pr279.test: Likewise, and tell to keep it in sync with its sister test. * tests/pr279-2.test: Likewise.