Handle reaching the top of a URL which searching for file ext

Should never reach this as most URL's will have a domain name that will
be caught as an extname.

1 files changed, 1 insertions, 0 deletions

diff --git a/Library/Homebrew/download_strategy.rb b/Library/Homebrew/download_strategy.rb
index 341947544..2774f2fad 100644
--- a/Library/Homebrew/download_strategy.rb
+++ b/Library/Homebrew/download_strategy.rb
@@ -306,6 +306,7 @@ class AbstractFileDownloadStrategy < AbstractDownloadStrategy
     url_pathname = Pathname.new(@url)
     until ext = url_pathname.extname[/[^?]+/]
       url_pathname = url_pathname.dirname
+      return if url_pathname.to_s == "."
     end
     ext
   end