Mimetype task on Ubuntu 14.04

[tresf]

The symptom is that the update-desktop-database utility is not working properly with makeself on Ubuntu 14.04. What does that have to do with makeself? I'm not entirely sure, but please read on...

This is an extremely strange bug and I'd like some help isolating the cause. I'll start by explaining my use-case... and the downstream bug report.

1. Script echos a foo.desktop file to /usr/share/applications/foo.desktop

foo-install.sh

   #!/bin/bash
   
   # CREATE MIMETYPE FILE
   echo "[Desktop Entry]
   Type=Application
   Name=Foo
   Exec=x-terminal-emulator
   Path=/
   Icon=utilities-terminal
   MimeType=application/x-foo;x-scheme-handler/foo;
   Terminal=false
   Comment=Foo Comment" > /usr/share/applications/foo.desktop
   chmod 755 /usr/share/applications/foo.desktop
   
   # REGISTER MIMETYPE FILE
   update-desktop-database

   
   ... then...

   makeself . foo-1.0.0.run "Foo Installer" "./foo-install.sh"

2. Test results

   xdg-open foo:bar

   Ubuntu Version	Makeself Version	Test Results
   12.04 x64	2.1.5	✅ Pass
   14.04 x64	2.2.0	⛔ Fail

Now I've tried many, many different test scenarios, such as using install, nohup, spawning a new process, etc, but the only thing that seems to fix the bug is to build the .run package from Ubuntu 12.04.

The expected behavior is that xdg-open foo:bar attempts to open x-terminal-emulator with the parameter bar, which is a registered URI/Mimetype for a web browser to use (similar in how Ubuntu registers apt:// for the Software Center).

The actual behavior is that the update-desktop-database command executes properly (I can pipe its output to a file and see it is executing) but the Ubuntu desktop doesn't register the command properly.

1. If a user manually runs sudo update-desktop-database from an interactive terminal after install, the Mimetype is registered properly, every single time.
2. To revert the mimetype installation for subsequent testing, remove /usr/share/applications/foo.desktop and run update-desktop-database again which will unregister the foo: mimetype.

So my question is... how does one begin troubleshooting a bug like this?

Again, the packages created on 12.04 don't experience this problem, even when being run on 14.04, so this leads me to believe it is a packaging bug somewhere, but I'm not sure how to debug further.

[tresf]

Seems to be a umask problem introduced with 842dedf so Ubuntu 12.04 hadn't had it yet.

Somewhat related e75285d.

Created work-around downstream via qzind/qz-print@ba51664.

Closing as invalid since this could be fixed downstream. Hopefully this will help out others using update-desktop-database with makeself.