We've been advised to state Red Hat's Copyright as

  Copyright Red Hat

In order to collect our current copyright notices, I've used the following
"loose options" for git-grep (bash syntax):

  loose_options=(-i -e copyright --and -e 'red.?hat')

Namely, the command

  git grep -h "${loose_options[@]}"

produces 464 matches (lines) in libnbd @ d169661119f6, and 861 matches
(lines) in nbdkit @ e36cfb6f.

Lest we replace strings too broadly, define the "strict pattern" as
follows (note that we assume LC_ALL=en_US.UTF-8):

  year='20[0-2][0-9]'
  year_range="$year(-$year)?"
  year_range_list="$year_range(, $year_range)*"
  year_range_list_opt="( $year_range_list)?"
  c_sym='(\(C\)|©)'
  company='Red Hat,? Inc\.'
  strict_pattern="[Cc]opyright $c_sym$year_range_list_opt $company"

The command

  git grep -h "${loose_options[@]}" \
  | grep -E -v -- "$strict_pattern"

produces zero lines in each of nbdkit and libnbd, meaning that the "strict
pattern" covers all matches fr...