When creating web application, should inherit cookies for site

I wanted to use GnomeWeb to run Tweetdeck as a saved web application. So I installed epiphany-browser, navigated to tweetdeck.twitter.com, logged in, and then attempted to save it as a web application. This all seemed to work, as well as Tweetdeck itself running apparently happily in there, and being OK with being moved to a screen with a different scaling factor (which Chrome's webapps don't handle, which is why I'm doing this.)

When I launched it, it invited me to log in. I clicked on the button, but it opened tweetdeck in Chrome, my default browser. I was already logged in there, so it just opened. There was no-where for me to log in the GnomeWeb web application.

I was at an impasse. There seems to be no way in the user interface to do this.

I have a workaround: I copied the cookies.sqlite file from ~/.config/epiphany to the webapp subdirectory (ie: ~/.config/epiphany/app-epiphany-tweetdeck-longhexnumber) and relaunched the webapp. This worked.

Suggestion for a fix could be that when saving a new web application, to copy the cookies in the main browser cookies list that relate to that web application's site. I didn't do it selectively though, I just copied the whole cookies file (I had not visited another site since installing it so there probably isn't anything else in there that tweetdeck doesn't need). It all seems to be working now, but this is just a commandline workaround.

ProblemType: Bug
DistroRelease: Ubuntu 17.10
Package: epiphany-browser 3.26.1-1ubuntu1
ProcVersionSignature: Ubuntu 4.13.0-14.15-generic 4.13.4
Uname: Linux 4.13.0-14-generic x86_64
NonfreeKernelModules: nvidia_uvm nvidia_drm nvidia_modeset nvidia
ApportVersion: 2.20.7-0ubuntu2
Architecture: amd64
CurrentDesktop: GNOME
Date: Thu Oct 5 18:17:26 2017
InstallationDate: Installed on 2017-07-30 (66 days ago)
InstallationMedia: Ubuntu-GNOME 17.04 "Zesty Zapus" - Release amd64 (20170412)
SourcePackage: epiphany-browser
UpgradeStatus: Upgraded to artful on 2017-08-22 (44 days ago)