bug#26576: -v when used with -C

[積丹尼 Dan Jacobson]

I want to do
$ cat file|some_program
but I must must exclude the UGLY line and its two neighbors.

OK I have found the UGLY line, and its two neighbors
$ grep -C 2 UGLY file
bla
bla
UGLY
bla
bla

but I have no way to exclude them before piping to some_program.