An updated launcher does not download missing or new assets. Deleting the launcher and allowing to be re-downloaded corrects the issue. 1.7.2 assets not downloaded when first launching profile uses different directory. Discovered due to sounds not working.

Setup: .minecraft_2 is an existing installation with 1.2.7 launcher, that has never launched 1.7.2

Verifying Test 1 (failure):
(1) Copy .minecraft_2 as .minecraft
(2) Run launcher, allowing update to 1.2.8
(3) Delete assets directory
(4) Run game
Result: Assets are not downloaded, game launches, no sound.

Verifying Test 2 (working):
(1) Copy a backup .minecraft installation with 1.2.7 launcher.
(2) Delete launcher.jar and launcher.pack.lzma
(3) Run Launcher
(4) Delete existing assets directory
(5) Run game
Result: Assets are downloaded, game launches, sound works.

Verifying Test 3 (failure):
(1) Copy a backup .minecraft installation with 1.2.7 launcher.
(2) Run launcher, allowing update to 1.2.8
(3) Create new 1.7.2 profile with alternate directory
(4) Run game
Result: Assets for 1.7.2, such as sounds.json are not downloaded, game launches, no sound.

Verifying Test 4 (working):
(1) Copy a backup .minecraft installation with 1.2.7 launcher.
(2) Delete launcher.jar, launcher.pack.lzma
(3) Run Launcher
(4) Create new 1.7.2 profile with alternate directory
(4) Run game
Result: Assets are downloaded, game launches, sound works.