/etc/bashrc exports PS1, but this is a shell parameter, not an environment variable. This "bug" is harmless, I post a patch just for the sake of correctness.
--- bashrc.old 2015-03-13 23:03:12.161160999 +0100
+++ bashrc.new 2015-03-19 17:56:42.495295025 +0100
@@ -14,5 +14,3 @@
# Colored prompt
PS1="\[\e[34;1m\]\u@\[\e[32;1m\]\h:\w\[\e[0m\] $ "
fi
-
-export PS1