formula_installer: prelude before fetch.

Library/Homebrew/cask/installer.rb

@@ -368,8 +368,8 @@ def cask_and_formula_dependencies
             fi.installed_on_request = false
             fi.show_header = true
             fi.verbose = verbose?
-            fi.fetch
             fi.prelude
+            fi.fetch
             fi.install
             fi.finish
           end

Library/Homebrew/cmd/install.rb

@@ -325,8 +325,8 @@ def install_formula(f)
     fi.build_bottle         = args.build_bottle?
     fi.interactive          = args.interactive?
     fi.git                  = args.git?
-    fi.fetch
     fi.prelude
+    fi.fetch
     fi.install
     fi.finish
   rescue FormulaInstallationAlreadyAttemptedError

Library/Homebrew/cmd/upgrade.rb

@@ -191,8 +191,8 @@ def upgrade_formula(f)
     end
     oh1 "Upgrading #{Formatter.identifier(f.full_specified_name)} #{upgrade_version} #{fi.options.to_a.join(" ")}"
 
-    fi.fetch
     fi.prelude
+    fi.fetch
 
     # first we unlink the currently active keg for this formula otherwise it is
     # possible for the existing build to interfere with the build we are about to

Library/Homebrew/formula_installer.rb

@@ -141,7 +141,6 @@ def install_bottle_for?(dep, build)
   def prelude
     Tab.clear_cache
     verify_deps_exist unless ignore_deps?
-    lock
     check_install_sanity
   end
 
@@ -221,6 +220,8 @@ def build_bottle_postinstall
   end
 
   def install
+    lock
+
     start_time = Time.now
     if !formula.bottle_unneeded? && !pour_bottle? && DevelopmentTools.installed?
       Homebrew::Install.perform_build_from_source_checks
@@ -969,9 +970,10 @@ def post_install
   end
 
   def fetch_dependencies
-    deps = compute_dependencies
+    return if ignore_deps?
 
-    return if deps.empty? || ignore_deps?
+    deps = compute_dependencies
+    return if deps.empty?
 
     deps.each { |dep, _options| fetch_dependency(dep) }
   end

Library/Homebrew/reinstall.rb

@@ -35,8 +35,8 @@ def reinstall_formula(f, build_from_source: false)
       fi.installed_as_dependency = tab.installed_as_dependency
       fi.installed_on_request    = tab.installed_on_request
     end
-    fi.fetch
     fi.prelude
+    fi.fetch
 
     oh1 "Reinstalling #{Formatter.identifier(f.full_name)} #{options.to_a.join " "}"
 

Library/Homebrew/test/support/helper/spec/shared_context/integration_test.rb

@@ -176,8 +176,8 @@ def install_test_formula(name, content = nil, build_bottle: false)
     setup_test_formula(name, content)
     fi = FormulaInstaller.new(Formula[name])
     fi.build_bottle = build_bottle
-    fi.fetch
     fi.prelude
+    fi.fetch
     fi.install
     fi.finish
   end