If a filename exists on commons, and a non-admin (ie without the (reupload-shared) right) tries to upload to the same name on enwiki, it displays;
A file with this name exists at the Wikimedia Commons. You can:
- go back and upload this file to Wikipedia using a different name.
- upload it to Commons, if your intent is to replace the image that already exists with a better version.
...ie literally, "$1" instead of, presumably, showing the file.
I've also documented this issue on the enwiki page where this problem came up;
(It'd be nice if, when fixed, someone could append a little note there)