Improve bottle error messages.

On installation or creation of a bottle error out of the current
machine does not support bottles.

References Homebrew/homebrew#16291.

Library/Homebrew/bottles.rb

@@ -10,7 +10,7 @@ def bottle_filename f, bottle_version=nil
 end
 
 def install_bottle? f
-  return true if ARGV.include? '--install-bottle'
+  return true if ARGV.include? '--install-bottle' and MacOS.bottles_supported?(true)
   return true if f.downloader and defined? f.downloader.local_bottle_path \
     and f.downloader.local_bottle_path
   not ARGV.build_from_source? \

Library/Homebrew/extend/ARGV.rb

@@ -130,7 +130,7 @@ module HomebrewArgvExtension
   end
 
   def build_bottle?
-    include? '--build-bottle' and MacOS.bottles_supported?
+    include? '--build-bottle' and MacOS.bottles_supported?(true)
   end
 
   def build_from_source?

Library/Homebrew/macos.rb

@@ -228,11 +228,24 @@ module MacOS extend self
     `/usr/sbin/pkgutil --pkg-info "#{id}" 2>/dev/null`.strip
   end
 
-  def bottles_supported?
+  def bottles_supported? raise_if_failed=false
     # We support bottles on all versions of OS X except 32-bit Snow Leopard.
-    (Hardware.is_64_bit? or not MacOS.version >= :snow_leopard) \
+    unless Hardware.is_64_bit? or MacOS.version >= :snow_leopard
-      and HOMEBREW_PREFIX.to_s == '/usr/local' \
+      return false unless raise_if_failed
-      and HOMEBREW_CELLAR.to_s == '/usr/local/Cellar' \
+      raise "Bottles are not supported on 32-bit Snow Leopard."
+    end
+
+    unless HOMEBREW_PREFIX.to_s == '/usr/local'
+      return false unless raise_if_failed
+      raise "Bottles are only supported with a /usr/local prefix."
+    end
+
+    unless HOMEBREW_CELLAR.to_s == '/usr/local/Cellar'
+      return false unless raise_if_failed
+      raise "Bottles are only supported with a /usr/local/Cellar cellar."
+    end
+
+    true
   end
 end