AppImageUpdate: Possible Github throttling problem? ("EOF from serverOther error?")

DISTRIB_ID=ManjaroLinux
DISTRIB_RELEASE=18.0.4
DISTRIB_CODENAME=Illyria
appimageupdatetool version 1-alpha (commit a62e9b9), build 409 built on 2019-06-15 20:35:29 UTC

Problem:

When updating a FreeCAD appimage using appimagetool, connection will die right before appimage is done updating.

Expecting

That running the appimagetool once will complete the update as expected.

Workaround

Run the same command (below) over again and the AppImage download successfully completes.

Specific Error

EOF from serverOther error? -1
...
...
zsync2: failed to retrieve from FreeCAD_0.19-17499-Linux-Conda_Py3Qt5_glibc2.12-x86_64.AppImage, status -1
100.00% done (363.00 of 363.00 MiB)...
Update failed!

Full Output

I can consistently reproduce this. Here is the terminal output:

$ ./appimageupdatetool-x86_64.AppImage -r FreeCAD_0.19-17445-Linux-Conda_Py3Qt5_glibc2.12-x86_64.AppImage 
Checking for updates...
Fetching release information for tag "0.19_pre" from GitHub API.
... done!
Starting update...

Fetching release information for tag "0.19_pre" from GitHub API.
Updating from GitHub Releases via ZSync
0% done
zsync2: Target file: /home/beast/bin/FreeCAD_0.19-17499-Linux-Conda_Py3Qt5_glibc2.12-x86_64.AppImage
zsync2: Reading seed file: FreeCAD_0.19-17445-Linux-Conda_Py3Qt5_glibc2.12-x86_64.AppImage
74.83% done (271.62 of 363.00 MiB)...
zsync2: Usable data from seed files: 77.366105%
zsync2: Renaming temp file
zsync2: Fetching remaining blocks
77.37% done (280.84 of 363.00 MiB)...
zsync2: Downloading from https://github-production-release-asset-2e65be.s3.amazonaws.com/5736080/6fb39280-b209-11e9-8c14-0f78a05d73ac?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIAIWNJYAX4CSVEH53A%2F20190729%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Date=20190729T213310Z&X-Amz-Expires=300&X-Amz-Signature=fdacc7ad03b1df62a7b21fa2572bc008b53081229720a0f39a04469e84120f75&X-Amz-SignedHeaders=host&actor_id=0&response-content-disposition=attachment%3B%20filename%3DFreeCAD_0.19-17499-Linux-Conda_Py3Qt5_glibc2.12-x86_64.AppImage&response-content-type=application%2Foctet-stream
99.37% done (360.72 of 363.00 MiB)...EOF from serverOther error? -1
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zsync2: failed to retrieve from FreeCAD_0.19-17499-Linux-Conda_Py3Qt5_glibc2.12-x86_64.AppImage, status -1
100.00% done (363.00 of 363.00 MiB)...
Update failed!