Don’t use bare percent literals.

Library/Homebrew/dev-cmd/audit.rb

@@ -716,11 +716,11 @@ class FormulaAuditor
     end
 
     if text =~ /system\s+['"]xcodebuild/
-      problem %(use "xcodebuild *args" instead of "system 'xcodebuild', *args")
+      problem %q(use "xcodebuild *args" instead of "system 'xcodebuild', *args")
     end
 
     if text =~ /xcodebuild[ (]["'*]/ && !text.include?("SYMROOT=")
-      problem %(xcodebuild should be passed an explicit "SYMROOT")
+      problem 'xcodebuild should be passed an explicit "SYMROOT"'
     end
 
     if text.include? "Formula.factory("
@@ -1002,9 +1002,9 @@ class FormulaAuditor
 
     case condition
     when /if build\.include\? ['"]with-#{dep}['"]$/, /if build\.with\? ['"]#{dep}['"]$/
-      problem %(Replace #{line.inspect} with "depends_on #{quoted_dep} => :optional")
+      problem %Q(Replace #{line.inspect} with "depends_on #{quoted_dep} => :optional")
     when /unless build\.include\? ['"]without-#{dep}['"]$/, /unless build\.without\? ['"]#{dep}['"]$/
-      problem %(Replace #{line.inspect} with "depends_on #{quoted_dep} => :recommended")
+      problem %Q(Replace #{line.inspect} with "depends_on #{quoted_dep} => :recommended")
     end
   end
 

Library/Homebrew/test/test_diagnostic.rb

@@ -146,7 +146,7 @@ class DiagnosticChecksTest < Homebrew::TestCase
       FileUtils.chmod 0755, file
       ENV["PATH"] = "#{path}#{File::PATH_SEPARATOR}#{ENV["PATH"]}"
 
-      assert_match %("config" scripts exist),
+      assert_match '"config" scripts exist',
         @checks.check_for_config_scripts
     end
   end

Library/Homebrew/test/test_exceptions.rb

@@ -13,7 +13,7 @@ class ExceptionsTest < Homebrew::TestCase
   end
 
   def test_formula_validation_error
-    assert_equal %(invalid attribute for formula 'foo': sha257 ("magic")),
+    assert_equal %q(invalid attribute for formula 'foo': sha257 ("magic")),
       FormulaValidationError.new("foo", "sha257", "magic").to_s
   end
 

Library/Homebrew/test/test_patch.rb

@@ -119,7 +119,7 @@ class ExternalPatchTests < Homebrew::TestCase
   end
 
   def test_inspect
-    assert_equal %(#<ExternalPatch: :p1 "file:///my.patch">), @p.inspect
+    assert_equal '#<ExternalPatch: :p1 "file:///my.patch">', @p.inspect
   end
 
   def test_cached_download

Library/Homebrew/test/test_string.rb

@@ -35,6 +35,6 @@ I'm not indented
   def test_inreplace_sub_failure
     s = "foobar".extend StringInreplaceExtension
     s.sub! "not here", "test"
-    assert_equal [%(expected replacement of "not here" with "test")], s.errors
+    assert_equal ['expected replacement of "not here" with "test"'], s.errors
   end
 end