Placed string is invisible in the Plastic and City texture packs

Verification builds:
1.6.0.30 Beta | Windows 10: Yes
1.5.3.0 | Windows 10: Yes

Summary:
String that has been placed in the Plastic and City texture packs is invisible.

Steps to Reproduce:

1. Start a world that has the Plastic or City texture pack applied
2. Place down some sting

Observed Results:
The placed sting does not have a visible texture.

Expected Results:
Placed string should be visible.

Screenshots/Videos attached: Yes

Notes: