unknown Sieve Capability `editheader'

[@lbutlr]

I am getting "error: error: require command: unknown Sieve capability `editheader’.” In sieve.log:

This is the start of .active_sieve

## Active
require [ "editheader", "regex", "variables", "fileinto", "envelope", "mailbox", "imap4flags" ];

Editheader is also listed in dovecot.conf

managesieve_sieve_capability = editheader fileinto reject envelope encoded-character vacation subaddress comparator-i;ascii-numeric relational regex imap4flags copy include variables body enotify environment mailbox date ihave