In Snapshot 13w39b, all text appears to be invisible. Nothing in particular seems to trigger this bug; simply starting the game. It seems that the text is visible for a short while as soon as the game is started, but afterwards becomes invisible. Resizing the window causes the text to turn only into blocks, as shown in the screenshots attached.

I have also tried this on Java 1.7, and it shows the same bug. The exact 'java -version' output from the 1.7 runtime is:
java version "1.7.0_25"
OpenJDK Runtime Environment (IcedTea 2.3.10) (7u25-2.3.10-1~deb7u1)
OpenJDK 64-Bit Server VM (build 23.7-b01, mixed mode)