TYPO3 Core

When uploading a file with space in filename via backend upload, TYPO3 changes spaces in filename into underlines.
 When uploading a changed version with the same name (with spaces!), TYPO3 asks as normal if it should overwrite the filename and does so. However, the file is NOT updated then, it remains the same old version of the file.
e.g.
 "this is testfile.pdf" is changed into "this_is_testfile.pdf" and if I upload a changed version of this file with "this is testfile.pdf", the old version remains on server through the process of renaming it with underlines.

When I upload with the renamed filename "this_is_testfile.pdf", TYPO3 correctly overwrites the file on server. It just does not overwrite when it has to change spaces into underlines...
This is a problem for editors as they very often do not think of giving filenames without spaces in the name... And they are getting problems when trying to update but TYPO3 doesn't as it should.
I hope it is clear what I mean, not everybody understands the problem here...
This was in version 12 already and I assume it continues in 13, could not test it yet. But remains problem for many editors using 12.