CurlDownloadStrategy: remove pointless type introspection

Library/Homebrew/download_strategy.rb

@@ -73,23 +73,20 @@ class CurlDownloadStrategy < AbstractDownloadStrategy
     unless @tarball_path.exist?
       begin
         _fetch
-      rescue Exception => e
-        if e.kind_of? ErrorDuringExecution
-          raise CurlDownloadStrategyError, "Download failed: #{@url}"
-        else
-          raise
-        end
+      rescue ErrorDuringExecution
+        raise CurlDownloadStrategyError, "Download failed: #{@url}"
       end
       ignore_interrupts { @temporary_path.rename(@tarball_path) }
     else
       puts "Already downloaded: #{@tarball_path}"
     end
-    return @tarball_path # thus performs checksum verification
   rescue CurlDownloadStrategyError
     raise if @mirrors.empty?
     puts "Trying a mirror..."
     @url = @mirrors.shift
     retry
+  else
+    @tarball_path
   end
 
   def stage