Be explicit about passing formulae names or instances to Tab

Library/Homebrew/cmd/doctor.rb

@@ -974,7 +974,7 @@ def check_for_non_prefixed_coreutils
 end
 
 def check_for_non_prefixed_findutils
-  default_names = Tab.for_formula('findutils').used_options.include? 'default-names'
+  default_names = Tab.for_name('findutils').used_options.include? 'default-names'
   if default_names then <<-EOS.undent
     Putting non-prefixed findutils in your path can cause python builds to fail.
     EOS

Library/Homebrew/formula_installer.rb

@@ -205,7 +205,7 @@ class FormulaInstaller
   end
 
   def install_dependency dep
-    dep_tab = Tab.for_formula(dep)
+    dep_tab = Tab.for_formula(dep.to_formula)
     dep_options = dep.options
     dep = dep.to_formula
 

Library/Homebrew/tab.rb

@@ -42,8 +42,11 @@ class Tab < OpenStruct
     end
   end
 
+  def self.for_name name
+    for_formula(Formula.factory(name))
+  end
+
   def self.for_formula f
-    f = Formula.factory(f)
     path = [f.opt_prefix, f.linked_keg].map{ |pn| pn.join(FILENAME) }.find{ |pn| pn.exist? }
     # Legacy kegs may lack a receipt. If it doesn't exist, fake one
     if path.nil? then self.dummy_tab(f) else self.from_file(path) end