erb_variable and migrating old rails app 2.0.2 --> 2.1 -->.

Hi,
I'm migrating an old rails app from 2.0* to 2.3 and eventually 3. I
thought I'd start with 2.1.* so as to progressively fix any issues that
cropped up.

Unfortunately both 2.1.2 and 2.1.1 fail to run my unit tests and
complain with the following message:

{:erb_variable==>"The erb variable will no longer be configurable. Use
the concat helper method instead of appending to it directly."} is not a
symbol

The changelog for 2.1.1 has: "Deprecate ActionView::Base.erb_variable.
Use the concat helper method instead of appending to it directly.
[Jeremy Kemper] "

2.1.0 works ok.

So it seems that there is something that is trying to use erb in a
deprecated way - and presumably it is not in the framework itself but in
my rails app and possibly any gems it is loading. Trouble is I'm having
no luck wading through the stack trace (rake test:units --trace).
Everything in the trace is either the framework itself or 3 other gems:
rake, rubygems and deprecated.
There is only one reference to my rails app, specifically to the line in
my environment.rb file that runs
   Rails::Initializer.run do |config| ...

Anyone have some sage advice on upgrading rails and locating/pinpointing
strange issues like the one with erb?

Regards,
Daniel Bush

The problem was the version of the deprecated gem I was using and not
erb or any of my rails code.
Rails 2.1.1+ works find with deprecated-3.0.0. I had an older version
which was blowing up in 2.1.1+.

Regards,
Daniel Bush