Copy env_proc when merging deps

Library/Homebrew/dependency.rb

@@ -100,7 +100,10 @@ class Dependency
       grouped = deps.group_by(&:name)
 
       deps.uniq.map do |dep|
-        dep.class.new(dep.name, grouped.fetch(dep.name).map(&:tags).flatten)
+        tags = grouped.fetch(dep.name).map(&:tags).flatten
+        merged_dep = dep.class.new(dep.name, tags)
+        merged_dep.env_proc = dep.env_proc
+        merged_dep
       end
     end
   end

Library/Homebrew/test/test_dependency_expansion.rb

@@ -66,4 +66,9 @@ class DependencyExpansionTests < Test::Unit::TestCase
     deps = [@foo2, @bar, @baz2, @qux]
     assert_equal deps, Dependency.expand(@f)
   end
+
+  def test_merger_preserves_env_proc
+    env_proc = @foo.env_proc = stub
+    assert_equal env_proc, Dependency.expand(@f).first.env_proc
+  end
 end