asset:precompile - incompatible encoding regexp match (ASCII-8BIT regexp with UTF-8 string)

asset:precompile - incompatible encoding regexp match (ASCII-8BIT regexp
with UTF-8 string)

Getting a weird error when trying to deploy a Rails app:
...
* executing "cd -- /rails/myapp/releases/20130919002235 &&
RAILS_ENV=production RAILS_GROUPS=assets bundle exec rake
assets:precompile"
[persephone] executing command
...
** [out :: persephone] rake aborted!
** [out :: persephone] Caught Encoding::CompatibilityError at
'["ok","(function() {': incompatible encoding regexp match (ASCII-8BIT
regexp with UTF-8 string)
** [out :: persephone] (in
/rails/myapp/releases/20130919002235/app/assets/javascripts/disk_files.js.coffee)
...
Thing is there's no regex patterns in that file.
I do have a few lines that contain backslashes in my coffeescript that
might be confusing the parser, but I don't believe this will be the
problem because .coffee should be compiled before .js:
#/app/assets/javascripts/disk_files.js.coffee
...
$('.hover-folder').hover \
(-> $(@).find('.show-on-hover').show()), \
(-> $(@).find('.show-on-hover').hide())
...
Anyone have any thoughts or know how to troubleshoot this?