Tell people to report URL/tap deprecations to the tap.

Rather than Homebrew/brew or Homebrew/homebrew-core.

Library/Homebrew/brew.rb

@@ -138,6 +138,14 @@ rescue RuntimeError, SystemCallError => e
   onoe e
   $stderr.puts e.backtrace if ARGV.debug?
   exit 1
+rescue MethodDeprecatedError => e
+  Utils::Analytics.report_exception(e)
+  onoe e
+  if e.issues_url
+    $stderr.puts "If reporting this issue please do so at (not Homebrew/brew or Homebrew/core):"
+    $stderr.puts "  #{Formatter.url(e.issues_url)}"
+  end
+  exit 1
 rescue Exception => e
   Utils::Analytics.report_exception(e)
   onoe e

Library/Homebrew/exceptions.rb

@@ -56,7 +56,9 @@ end
 
 class FormulaSpecificationError < StandardError; end
 
-class MethodDeprecatedError < StandardError; end
+class MethodDeprecatedError < StandardError
+  attr_accessor :issues_url
+end
 
 class FormulaUnavailableError < RuntimeError
   attr_reader :name

Library/Homebrew/formulary.rb

@@ -151,6 +151,11 @@ class Formulary
       FileUtils.rm_f(path)
       curl url, "-o", path
       super
+    rescue MethodDeprecatedError => e
+      if url =~ %r{github.com/([\w-]+)/homebrew-([\w-]+)/}
+        e.issues_url = "https://github.com/#{$1}/homebrew-#{$2}/issues/new"
+      end
+      raise
     end
   end
 
@@ -202,6 +207,13 @@ class Formulary
     rescue FormulaUnavailableError => e
       raise TapFormulaUnavailableError.new(tap, name), "", e.backtrace
     end
+
+    def load_file
+      super
+    rescue MethodDeprecatedError => e
+      e.issues_url = formula.tap.issues_url || formula.tap.to_s
+      raise
+    end
   end
 
   class NullLoader < FormulaLoader