File Upload: Could not add a couple very large FITs files, found a few related issues.

[kcondon]

A user asked us to bypass the current file upload limit of 2.5GB to upload 6 and 4GB fits files. I temporarily increased the file upload limit and tried through a Chrome browser. Both files appeared to upload but stopped at the end of the progress meter and did not add the files to the uploaded but not saved list on the addfiles dataset page.

I had initially tried uploading just one file and it showed the stopping at the end of upload meter behavior and after waiting for several minutes to then add the file to the uploaded list (I assumed it was extracting FITS metadata) I tried clicking the upload files button and selected the other file to perhaps wake the page up. What it did was begin uploading both files all over again. After waiting for both to reach the end and then waiting an additional 15 mins to complete, I clicked save changes and nothing was saved.

So the following appear to be issues:

1. Uploading a large FITS file appears to upload, reach the end of the upload meter but then never add the file to the uploaded file list.
2. The upload files button remains enabled while a file is being uploaded. I'm told it shouldn't and clicking it to add another file while an upload is in progress causes all files to be uploaded again.
3. The save changes button seems to be always enabled even though there is nothing to save.

For reference, the two test files belonged to version 2 of this dataset:
doi:10.7910/DVN/IYHHQ1
L1495-B218_NH3_11.fits
L1495-B218_NH3_22.fits

[kcondon]

Closing this as related to #3634 though the root cause may be different. Both file types undergo additional processing after upload but before the upload meter disappears so it may be happening during that phase. Have linked to this ticket from that for additional details.