notmuch shows tag which is not on any email

[Gregor Zattler <telegraph@gmx.net>]

Dear notmuch developers,

does notmuch remember tags even if at time of query there is no
message tagged with the respective tag?:

$ notmuch search --output=tags '*' | grep telegraph
EA%3Dtelegraph%40gmx%2Enet
EA=telegraph@gmx.net


$ notmuch count  -- is:EA%3Dtelegraph%40gmx%2Enet
0


$ notmuch count  -- is:/EA.*telegraph/
4498


There is no invisible character or some such:
$ notmuch search --output=tags '*' | grep telegraph | head -n 1 | wc -c
27


I might have done something wrong while experimenting with this
tags and  'EA%3Dtelegraph%40gmx%2Enet' may be a leftover.  I
would like to remove it but since no message matches it's not
possible to remove it from messages and therefore the tag remains:

$ notmuch tag +EA=telegraph@gmx.net  -- is:/EA.*telegraph/
$ notmuch search --output=tags '*' | grep telegraph
EA%3Dtelegraph%40gmx%2Enet
EA=telegraph@gmx.net


I tried to utilise emacs to remove the tag, but notmuch-emacs
does not show 'EA%3Dtelegraph%40gmx%2Enet' in notmuch-hello's
'All tags' section.



Why is said tag in the tags listing, how to get rid of it?


Thanks, Gregor