[Merkaartor] Reproducing "412 precondition failed" errors and merkaartor error-handling behaviour

[Sven Lankes]

During my usual mapping-routine I quite often have the case where I'm
presented a "412 precondition failed" error by merkaartor.

This error isn't handled gracefully by merkaartor because after the
failure any subsequent upload will again try to re-upload the changes.

I'm having a hard time pinpointing the exact circumstances of the error
(although I did find the following on the josm-trac:

    Generally speaking, you get an 412 error when you want to delete
    something that is still used by something else, e.g. you download a
    bounding box, and then remove some of the superfluous nodes in a way,
    but don't realize that these were actually intersections because the
    server doesn't return ways outside the bounding box you requested.)

The problem is that the error only occurs during uploads and I don't
want to do too much debug-uploading to the production osm-servers. Is
there a dev-osm-server that I could use to reproduce the problem? Maybe
one where the database is recreated from scratch every day?

-- 
sven === jabber/xmpp: sven at lankes.net