Build from source on bottle pour failure.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>

Library/Homebrew/formula_installer.rb

@@ -92,9 +92,17 @@ class FormulaInstaller
 
     @@attempted << f
 
+    poured_bottle = false
+    begin
       if pour_bottle?
         pour
-    else
+        poured_bottle = true
+      end
+    rescue
+      opoo "Bottle installation failed: building from source."
+    end
+
+    unless poured_bottle
       build
       clean
     end