don't trigger VCS when patching

When patching read-only files, patch can try to check-out from
a VCS system when other conditions are met, such as environmental
variables being set.

Homebrew never wants to trigger this behavior, so pass --get=0.

Closes Homebrew/homebrew#26277.

Library/Homebrew/formula.rb

@@ -635,7 +635,7 @@ class Formula
         when :bzip2 then with_system_path { safe_system "bunzip2", p.compressed_filename }
       end
       # -f means don't prompt the user if there are errors; just exit with non-zero status
-      safe_system '/usr/bin/patch', '-f', *(p.patch_args)
+      safe_system '/usr/bin/patch', '-g', '0', '-f', *(p.patch_args)
     end
   end