Installer does not process copy errors correctly, proceeds to the next phase and hangs

[monsta]

During the installation to a USB flash drive, the installer says "Setting hostname" and does nothing after that.
Here's the output from the terminal:

gksu live-installer
glibtop: Non-standard uts for running kernel:
release 3.11-2-486=3.11.0 gives version code 199424

No translation found, switching back to English
Color: #ff0001
Image: /usr/share/live-installer/timezone/timezone_-6.0.png
Color: #ff2a2a
Image: /usr/share/live-installer/timezone/timezone_-5.0.png
Failed to mount /dev/sdb3
## INSTALLATION
Template path: /usr/share/live-installer/slideshow/template.html
Content path does not exist: /usr/share/live-installer/slideshow/office.html
--> Installation started
EXECUTING: 'mkfs.ext4 /dev/sdb1'
--> Mounting partitions
------ Mounting /lib/live/mount/medium/live/filesystem.squashfs on /source/
EXECUTING: 'mount -o loop -t squashfs /lib/live/mount/medium/live/filesystem.squashfs /source/'
------ Mounting partition /dev/sdb1 on /target/
EXECUTING: 'mount -t ext4 /dev/sdb1 /target'
------ Mounting /dev/sdb3 on /target/home
EXECUTING: 'mount -t ext4 /dev/sdb3 /target/home'
--> Indexing files
--> Copying files
File "/usr/lib/live-installer/installer.py", line 188, in init_install
self.do_copy_file(sourcepath, targetpath)
--> Writing hostname
File "/usr/lib/live-installer/installer.py", line 341, in finish_install
hostnamefh = open("/target/etc/hostname", "w")

Originally reported in this thread.

[monsta]

Another report of installer failing and stopping in similar way during the install to a USB flash drive.
This time it shows "Setting keyboard options" in the GUI and does nothing after that. The point where it stops is different, but the manner is the same, which can be seen in the following output from the terminal:

mint@mint ~ $ gksu live-installer
glibtop: Non-standard uts for running kernel:
release 3.11-2-amd64=3.11.0 gives version code 199424

Color: #550000
Image: /usr/share/live-installer/timezone/timezone_-10.0.png
Coords: 165.0 169.0
Closest timezone America/Indiana/Indianapolis
Color: #ff2a2a
Image: /usr/share/live-installer/timezone/timezone_-5.0.png
Color: #ff2a2a
Image: /usr/share/live-installer/timezone/timezone_-5.0.png
Coords: 165.0 157.0
Closest timezone America/Rainy_River
Color: #ff0001
Image: /usr/share/live-installer/timezone/timezone_-6.0.png
Color: #ff0001
Image: /usr/share/live-installer/timezone/timezone_-6.0.png
 ## INSTALLATION
Template path: /usr/share/live-installer/slideshow/template.html
Content path does not exist: /usr/share/live-installer/slideshow/office.html
 --> Installation started
EXECUTING: 'mkfs.ext4 /dev/sdb1'
 --> Mounting partitions
 ------ Mounting /lib/live/mount/medium/live/filesystem.squashfs on /source/
EXECUTING: 'mount -o loop -t squashfs /lib/live/mount/medium/live/filesystem.squashfs /source/'
 ------ Mounting partition /dev/sdb1 on /target/
EXECUTING: 'mount -t ext4 /dev/sdb1 /target'
 --> Indexing files
 --> Copying files
  File "/usr/lib/live-installer/installer.py", line 188, in init_install
    self.do_copy_file(sourcepath, targetpath)
 --> Writing hostname
 --> Setting the locale
chroot /target/ /bin/sh -c "locale-gen"
chroot /target/ /bin/sh -c "update-locale LANG='en_US.UTF-8'"
chroot /target/ /bin/sh -c "update-locale LANG=en_US.UTF-8"
 --> Setting the timezone
 --> Localizing packages
 --> Setting the keyboard
  File "/usr/lib/live-installer/installer.py", line 389, in finish_install
    consolefh = open("/target/etc/default/console-setup", "r")

Originally reported in this thread.

[monsta]

Ok, I figured it out. USB drives don't matter, what matters is that the installer doesn't stop after catching the exception in do_copy_file. Instead it proceeds to the next phase. There it catches another exception while trying to set up something in the target filesystem, and the GUI finally hangs.

Here's another example. I've set up a virtual machine with 512 MB virtual hard drive so the installer would 100% fail while copying the files.

 --> Indexing files
 --> Copying files
  File "/usr/lib/live-installer/installer.py", line 188, in init_install
    self.do_copy_file(sourcepath, targetpath)
 --> Writing hostname
  File "/usr/lib/live-installer/installer.py", line 354, in finish_install
    hostsfh.close()

At the time when the exception in do_copy_file has been caught, the GUI immediately changed from "Copying files" to "Setting hostname" and froze. This is wrong. The GUI should show a message about copy failure and stop the installation right there.

[monsta]

Fixed in git. The error dialog is now shown, and the installer stops installation and exits after that. Closing.