User mime type not used in nautilus

[Eero Aaltonen]

I have a user local mime type definition .local/share/mime/graphml+xml.xml

```
<?xml version="1.0" encoding="utf-8"?>
<mime-type xmlns="http://www.freedesktop.org/standards/shared-mime-info" type="application/graphml+xml">
  <!--Created automatically by update-mime-database. DO NOT EDIT!-->
  <comment>GraphML file</comment>
  <icon name="yicon32"/>
  <glob-deleteall/>
  <glob pattern="*.graphml"/>
</mime-type>
```

and have registered it with `update-mime-database ~/.local/share/mime`

Querying the mime database from the command line gives correct results:
$ gio mime application/graphml+xml
Default application for “application/graphml+xml”: yed.desktop
Registered applications:
 yed.desktop
Recommended applications:
 yed.desktop

In Ubuntu 16.04 nautilus would also use the new mime type and the associated default application.

In Ubuntu 18.04 this is however not the case.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: nautilus 1:3.26.4-0~ubuntu18.04.5
ProcVersionSignature: Ubuntu 4.15.0-76.86-generic 4.15.18
Uname: Linux 4.15.0-76-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.9
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Wed Feb 19 17:03:23 2020
InstallationDate: Installed on 2018-01-10 (769 days ago)
InstallationMedia: Ubuntu 16.04.3 LTS "Xenial Xerus" - Release amd64 (20170801)
SourcePackage: nautilus
UpgradeStatus: Upgraded to bionic on 2019-02-12 (372 days ago)
usr_lib_nautilus:

[Sebastien Bacher (seb128)]

Thank you for your bug report, that's probably something you should report upstream on https://gitlab.gnome.org/GNOME/nautilus/issues/