Reintegrate can only be used if revisions XX through YY were previously merged ...

Hi,

I'm trying to do a catchup merge between two branches (incidentally within
the Subversion website tree) but I fail and I don't have enough
understanding to know what is wrong.

I have a working copy from https://svn.apache.org/repos/asf/subversion/site

In $WC/staging/, I run:
[[[
$ svn merge ^/subversion/site/publish
svn: E195016: Reintegrate can only be used if revisions 1812681 through
1915353 were previously merged from
https://svn.apache.org/repos/asf/subversion/site/staging to the reintegrate
source, but this is not the case:
  subversion/site/publish
    Missing ranges:
/subversion/site/staging:1898163-1898164,1898168,1898183,1899002,1899183,1899186,1899621,1905961,1905965,1909457
]]]

The listed revisions all seem to be authored directly in staging and not
yet merged to publish (related to the upcoming 1.15 release).

What has gone wrong and what can we do to get back into a working state?

Kind regards,
Daniel Sahlberg