~/.cache/upstart/mtp-server.log grows very large, filling /home and rendering phone unusable

[Jamie Strandboge]

I have 7.6G of music in /home/phablet/Music. /home is currently:
/dev/mmcblk0p23 13G 12G 1.2G 91% /home

Unfortunately, ~/.cache/upstart/mtp-server.log grows very fast. Eg:
# ls -lh ./mtp-server.log
-rw-r----- 1 phablet phablet 1.2G Mar 12 12:27 ./mtp-server.log

$ wc -l ./mtp-server.log
15626025 ./mtp-server.log

When this happens, the user session is very grumpy-- apps can't launch, network indicator can't connect to networks, etc, etc. It is mostly filled with entries of the form:
...
 format: b902
   "/home/phablet/Music/zappa, frank/Frank_Zappa - One_Size_Fits_All - 01 - Inca_Roads.ogg" handle: 6bb parent: 6ae
android::MtpObjectFormat android::UbuntuMtpDatabase::guess_object_format(std::string) extension: .ogg
 format: b902
   "/home/phablet/Music/zappa, frank/Frank Zappa - Zappa in New York (disc 2) - 04 - The Black Page Drum Solo - Black Page #1.ogg" handle: 6bc parent: 6ae
android::MtpObjectFormat android::UbuntuMtpDatabase::guess_object_format(std::string) extension: .ogg
...

However, it is very noisy and seems to run away. Ie, grepping for a single picture in the Pictures folder:
$ egrep image20140309_0002.jpg ./mtp-server.log | wc -l
3324

This is after less than a day of use-- and I didn't reboot, connect via USB, etc 3324 times today. :)

Workaround: when phone is unusable, check how much /home is filled, if 100%, rm -f ~/.cache/upstart/mtp-server.log and reboot.