I once reviewed code for a company that got purchased. I took less than a few hours to reach conclusion. There were 7 developers and in 2 months only one was writing code. The entire team but that one developer was fired. Twitter has grown a reputation for being slow and a rest and vest haven. Won't be surprised if they are looking for people not writing code.
On a different note, If you're in a large org and all you are doing is fixing bugs, you are doing yourself a disservice and so is the org in the way they are treating you. Unless you are the original author of that code. When people don't fix their own bugs, they tend to repeat it in other places. When people tend to fix code they didn't write nor have the proper context on why the code was written like that, they tend to turn it into a mess. IMHO, Developers should be writing new code and maintaining their own code. Never reward developers by giving them more new code and stopping them from maintenance.
On a different note, If you're in a large org and all you are doing is fixing bugs, you are doing yourself a disservice and so is the org in the way they are treating you. Unless you are the original author of that code. When people don't fix their own bugs, they tend to repeat it in other places. When people tend to fix code they didn't write nor have the proper context on why the code was written like that, they tend to turn it into a mess. IMHO, Developers should be writing new code and maintaining their own code. Never reward developers by giving them more new code and stopping them from maintenance.