I worked with a good dev at one of my previous jobs, but one of his faults was that he was a bit scattered and would sometimes forget things.

The story goes that one day we had this massive bug on our web app and we had a large portion of our dev team trying to figure it out. We thought we narrowed down the issue to a very specific part of the code, but something weird happened. No matter how often we looked at the piece of code where we all knew the problem had to be, no one could see any problem with it. And there want anything close to explaining how we could be seeing the issue we were in production.

We spent hours going through this. It was driving everyone crazy. All of a sudden, my co-worker (one referenced above) gasps “oh shit.” And we’re all like, what’s up? He proceeds to tell us that he thinks he might have been testing a line of code on one of our prod servers and left it in there by accident and never committed it into the actual codebase. Just to explain this - we had a great deploy process at this company but every so often a dev would need to test something quickly on a prod machine so we’d allow it as long as they did it and removed it quickly. It was meant for being for a select few tasks that required a prod server and was just going to be a single line to test something. Bad practice, but was fine because everyone had been extremely careful with it.

Until this guy came along. After he said he thought he might have left a line change in the code on a prod server, we had to manually go in to 12 web servers and check. Eventually, we found the one that had the change and finally, the issue at hand made sense. We never thought for a second that the committed code in the git repo that we were looking at would be inaccurate.

Needless to say, he was never allowed to touch code on a prod server ever again.