Direct upload multiple files

[haarli]

This pull request addresses and fixes issue #8408.

As stated in the issue, I'm not really sure about the intention of the original code, in particular the splice-method with the 'i+1' deleteCount parameter. So a review would be great.

Generally, this seems to be a concurrency problem, there might still be concurrency issues with this bugfix, but it works much better

Closes #8408

[qqmyers]

I think this makes sense - fixing an embarrassing bug :-). It's been a while, but I think the code is just scanning the list of pending files and trying to pull one out to work on. It should (with the fix) just pull one entry out of the list (not necessarily the first entry) to process. The original bug would remove more than one entry (more the larger i is - param 2 is number of entries to remove) and only work on the first one. Not a race per se, but a bug that would ignore some files. (I'd have to dig further to see how/when the request to this method wouldn't be trying to get the first element (i=0, which works OK with the bug) but I could imagine it being very intermittent.)

Thanks for the fix!

[haarli]

Thank you for the prompt reply and merge.
Yes, I thought so, too. Just wasn't sure about the i+1 and if there was an idea behind it. But probably just a confusion between (startIndex, endIndex), like many methods use, and (startIndex, deleteCount), like splice uses. Not embararrassing at all.

Thanks again!