Install `discourse_image_optim` gem for now.

Gemfile

@@ -66,7 +66,9 @@ gem 'unf', require: false
 
 gem 'email_reply_trimmer', '0.1.6'
 
-gem 'image_optim'
+# TODO Use official image_optim gem once https://github.com/toy/image_optim/pull/149
+# is merged.
+gem 'discourse_image_optim', require: 'image_optim'
 gem 'multi_json'
 gem 'mustache'
 gem 'nokogiri'

Gemfile.lock

@@ -79,6 +79,12 @@ GEM
     discourse-qunit-rails (0.0.9)
       railties
     discourse_fastimage (2.0.3)
+    discourse_image_optim (0.24.4)
+      exifr (~> 1.2, >= 1.2.2)
+      fspath (~> 3.0)
+      image_size (~> 1.5)
+      in_threads (~> 1.3)
+      progress (~> 3.0, >= 3.0.1)
     domain_name (0.5.25)
       unf (>= 0.0.5, < 1.0.0)
     email_reply_trimmer (0.1.6)
@@ -126,12 +132,6 @@ GEM
       domain_name (~> 0.5)
     http_accept_language (2.0.5)
     i18n (0.8.1)
-    image_optim (0.24.2)
-      exifr (~> 1.2, >= 1.2.2)
-      fspath (~> 3.0)
-      image_size (~> 1.5)
-      in_threads (~> 1.3)
-      progress (~> 3.0, >= 3.0.1)
     image_size (1.5.0)
     in_threads (1.4.0)
     jmespath (1.3.1)
@@ -405,6 +405,7 @@ DEPENDENCIES
   certified
   discourse-qunit-rails
   discourse_fastimage (= 2.0.3)
+  discourse_image_optim
   email_reply_trimmer (= 0.1.6)
   ember-handlebars-template (= 0.7.5)
   ember-rails (= 0.18.5)
@@ -423,7 +424,6 @@ DEPENDENCIES
   hiredis
   htmlentities
   http_accept_language (~> 2.0.5)
-  image_optim
   listen
   logster
   lru_redux