xdg-document-portal 1.0.2-1ubuntu1 crashes when trying to save to a non-existant file

[James Henstridge]

When using the desktop portal API to save a file, the xdg-document-portal service crashes if we try to save to a new file name.

Steps to reproduce:

1. On an Ubuntu 18.10 system, install the test-snapd-portal-client snap:

    snap install --edge test-snapd-portal-client

2. run the save-file test:

    test-snapd-portal-client save-file "foo"

3. in the file chooser, select a file name that does not exist.

Actual results:

The command exits with the following error (eliding the traceback):

    ConnectionAbortedError: [Errno 103] Software caused connection abort: '/run/user/1000/doc/eca716d3/xyz.txt'

Furthermore, "systemctl --user status xdg-document-portal.service" reports the following error:

    Jan 07 17:38:06 scruffy xdg-document-portal[30685]: error: Invalid id snap.test-snapd-portal-client: Names must contain at least 2 periods
    Jan 07 17:38:06 scruffy xdg-document-portal[30685]: error: **
    Jan 07 17:38:06 scruffy xdg-document-portal[30685]: xdg-desktop-portal:ERROR:document-portal/document-portal-fuse.c:206:xdp_inode_destroy: assertion failed: (inode->dir_fd == -1)

Expected results:

The file should be created with the contents "foo".

The problem is not present with xdg-desktop-portal 1.0.3. I suspect the fix is one of these extra patches alexl suggested we take: https://bugs.launchpad.net/ubuntu/+source/xdg-desktop-portal/+bug/1691649/comments/10