Has anyone ever seen the common wire connected to the red wire??
This may be about terms and names.
The craze of smart thermostats like the Nest has made everybody interested in a heretofore-unused-by-thermostats wire called the "C" wire. And C is for common; in thermostat wiring it's analogous to mains Neutral or electronics GND. 98% of the time when someone says "common" they're after that.
However, old steam thermostats like yours also have a wire which is the power source, and is called the R wire. The thermostat connects R to call-for-heat (W), fan (G), call-for-AC (Y), etc. It is, well, a kind of common... though you would be unwise to call it that today, due to the confusion it would create with smart 'stat wiring.
And the conventional color for the R wire is, in fact, red.
However these are only conventions. Given that every thermostat has R, I would expect them to use Red for R. However I suppose if someone was eccentric they could use red for C. I wouldn't, though.
Your thermostat does not need and cannot use the C wire, so that's not an issue for you. Prepare for the day it is!