Move 10.11 warning to doctor, pre-install, and post-failure

Fixes Homebrew/homebrew#40778.

1 files changed, 5 insertions, 0 deletions

diff --git a/Library/Homebrew/exceptions.rb b/Library/Homebrew/exceptions.rb
index 7eb053a7c..bad8d2c2d 100644
--- a/Library/Homebrew/exceptions.rb
+++ b/Library/Homebrew/exceptions.rb
@@ -216,6 +216,11 @@ class BuildError < RuntimeError
       puts "These open issues may also help:"
       puts issues.map{ |i| "#{i['title']} (#{i['html_url']})" }.join("\n")
     end
+
+    if MacOS.version >= "10.11"
+      require "cmd/doctor"
+      opoo Checks.new.check_for_unsupported_osx
+    end
   end
 end