When using Special:Upload over the last ~2 days, the following header line is added to the beginning of the wikitext, even when it is already included in the wikitext given by the user:
== {{int:filedesc}} ==See for example this file, where the upload comment shows only one header line in the wikitext, but a second line was added by the software.
This exact same issue occurred 8 years ago:
T187302
Seems related to cbea8bfc8075eff4bd79aab4cfa4553fdd6ac833 / T252681, which does something with the upload text.
Change #1328367 had a related patch set uploaded (by Mr. Starfleet Command; author: Mr. Starfleet Command):
[mediawiki/core@master] Follow section headers by single newline instead of double newline
@Pi.1415926535 Thanks for reporting, @Umherirrender thanks for adding me!
I believe this issue can be fixed by tweaking the code to add a single newline after headers instead of adding two as is currently done. Luckily I already had just such a patch as a WIP for other reasons, but now that I know about this issue I've updated its commit message and marked it as active.
Change #1337332 had a related patch set uploaded (by Mr. Starfleet Command; author: Mr. Starfleet Command):
[mediawiki/extensions/GrowthExperiments@master] Update unit tests to use correct header spacing
Change #1337384 had a related patch set uploaded (by Mr. Starfleet Command; author: Mr. Starfleet Command):
[mediawiki/extensions/GrowthExperiments@master] Temporarily remove unit tests involving header spacing
Change #1337384 merged by jenkins-bot:
[mediawiki/extensions/GrowthExperiments@master] Temporarily remove unit tests involving header spacing
Change #1328367 merged by jenkins-bot:
[mediawiki/core@master] Follow section headers by single newline instead of double newline
Change #1337332 merged by jenkins-bot:
[mediawiki/extensions/GrowthExperiments@master] Update unit tests to use correct header spacing