"svn pget svn:externals -r <rev> . -R" dramatically slow

Hello Users,

Original issue: https://issues.apache.org/jira/browse/SVN-4681

Just discovered a really strange case where exactly titled command bring really slow response.

The repository contains more than 1000 revisions. The WC is in the middle, say at rev 1193 (the current), the show log shows 1191 at the last revision, the HEAD revision say 1300.
Trying to cd into WC directory and run the command. Needs about 1 minute to wait it's response. The Process Hacker shows traffic with the server up to about 2MB.

If try to run command w/o -R flag - command returns immediately.

The content of the externals property without the -R flag is:
https://domain.ab/svn/proj2/trunk - ^/../proj3/trunk/cmake cmake_proj3
^/solutions/project1/sdk proj2-sdk

The content of the externals property with the -R flag is:
https://domain.ab/svn/proj2/trunk - ^/../proj3/trunk/cmake cmake_proj3
^/solutions/project1/sdk proj2-sdk
https://domain.ab/svn/proj2/trunk/proj2-gui -
https://domain.ab/svn/proj2/trunk/proj2-gui/lib/Resource/Files -

I think the 2 last records draws the svn mad and it begin to crawl the server for something for about 1 minute.

I tries variations of the command. For example all these having the same result as above:
svn pget svn:externals -r "1193" "https://domain.ab/svn/proj2/trunk" -R --non-interactive
svn pget svn:externals -r "1193" "https://domain.ab/svn/proj2/trunk@1193" -R --non-interactive
svn pget svn:externals "https://domain.ab/svn/proj2/trunk@1193" -R --non-interactive

Dig a bit further and found this:
svn info https://domain.ab/svn/proj2/trunk/proj2-gui
svn: warning: W170000: URL 'https://domain.ab/svn/proj2/trunk/proj2-gui' non-existent in revision 1300
svn: E200009: Could not display info for all targets because some targets don't exist

Seems the 2 last records reference URL's what does not exist anymore in the HEAD.

These 2 records are left after an upgrade from a previous version of database, but why is the svn runs so slow about it? Anyway, i can't just cleanup the externals because they are from 3dparty repository in which i have no access.

-- 
Best regards,
 Andry                          mailto:andry_at_inbox.ru