Tweak preserve link status on reinstall/upgrade.

Treat a `brew install` command as normal i.e. link by default unless
keg-only and only specify whether a keg should be linked when upgrading
or reinstalling. Also, adjust the naming accordingly so it's more
obvious that this is the case.

Library/Homebrew/cmd/reinstall.rb

@@ -23,6 +23,7 @@ module Homebrew
   def reinstall_formula(f)
     if f.opt_prefix.directory?
       keg = Keg.new(f.opt_prefix.resolved_path)
+      keg_had_linked_opt = true
       keg_was_linked = keg.linked?
       backup keg
     end
@@ -38,7 +39,7 @@ module Homebrew
     fi.build_bottle         = ARGV.build_bottle? || (!f.bottled? && f.build.bottle?)
     fi.interactive          = ARGV.interactive?
     fi.git                  = ARGV.git?
-    fi.keg_was_linked       = keg_was_linked
+    fi.link_keg             = keg_was_linked if keg_had_linked_opt
     fi.prelude
 
     oh1 "Reinstalling #{f.full_name} #{options.to_a.join " "}"

Library/Homebrew/cmd/upgrade.rb

@@ -101,6 +101,12 @@ module Homebrew
   end
 
   def upgrade_formula(f)
+    if f.opt_prefix.directory?
+      keg = Keg.new(f.opt_prefix.resolved_path)
+      keg_had_linked_opt = true
+      keg_was_linked = keg.linked?
+    end
+
     formulae_maybe_with_kegs = [f] + f.old_installed_formulae
     outdated_kegs = formulae_maybe_with_kegs
                     .map(&:linked_keg)
@@ -118,6 +124,7 @@ module Homebrew
     fi.options &= f.options
     fi.build_bottle = ARGV.build_bottle? || (!f.bottled? && f.build.build_bottle?)
     fi.installed_on_request = !ARGV.named.empty?
+    fi.link_keg             = keg_was_linked if keg_had_linked_opt
     if tab
       fi.installed_as_dependency = tab.installed_as_dependency
       fi.installed_on_request  ||= tab.installed_on_request

Library/Homebrew/formula_installer.rb

@@ -37,17 +37,11 @@ class FormulaInstaller
   mode_attr_accessor :show_summary_heading, :show_header
   mode_attr_accessor :build_from_source, :force_bottle
   mode_attr_accessor :ignore_deps, :only_deps, :interactive, :git
-  mode_attr_accessor :verbose, :debug, :quieter, :keg_was_linked
+  mode_attr_accessor :verbose, :debug, :quieter, :link_keg
 
   def initialize(formula)
     @formula = formula
-    @rack_was_present = formula.rack.directory?
-    @keg_was_linked = if formula.linked_keg.directory?
-      keg = Keg.new(formula.linked_keg.resolved_path)
-      keg.linked?
-    else
-      false
-    end
+    @link_keg = !formula.keg_only?
     @show_header = false
     @ignore_deps = false
     @only_deps = false
@@ -532,6 +526,7 @@ class FormulaInstaller
 
     if df.linked_keg.directory?
       linked_keg = Keg.new(df.linked_keg.resolved_path)
+      keg_had_linked_keg = true
       keg_was_linked = linked_keg.linked?
       linked_keg.unlink
     end
@@ -551,7 +546,7 @@ class FormulaInstaller
     fi.verbose            = verbose?
     fi.quieter            = quieter?
     fi.debug              = debug?
-    fi.keg_was_linked     = keg_was_linked
+    fi.link_keg           = keg_was_linked if keg_had_linked_keg
     fi.installed_as_dependency = true
     fi.installed_on_request = false
     fi.prelude
@@ -722,13 +717,7 @@ class FormulaInstaller
   end
 
   def link(keg)
-    link_formula = if @rack_was_present
-      keg_was_linked?
-    else
-      !formula.keg_only?
-    end
-
-    unless link_formula
+    unless link_keg
       begin
         keg.optlink
       rescue Keg::LinkError => e

Library/Homebrew/test/bottle_hooks_spec.rb

@@ -12,8 +12,7 @@ describe Homebrew::Hooks::Bottles do
       local_bottle_path: nil,
       bottle_disabled?: false,
       some_random_method: true,
-      linked_keg: Pathname("foo"),
-      rack: Pathname("bar"),
+      keg_only?: false,
     )
   end