grep 2.21 incorrectly handles a -P regular expression that 2.20 handled correctly. Thanks for looking into this.
$ cat file Here's a line. This line has one blank line above it. This line has two blank lines above it. This line has three blank lines above it. This line has four blank lines above it. $ grep-2.20/src/grep -Pzo '(?<=\n\n\n).*' file This line has two blank lines above it. This line has three blank lines above it. This line has four blank lines above it. $ grep-2.21/src/grep -Pzo '(?<=\n\n\n).*' file This line has two blank lines above it.
