I've been digging on the Internet, for a solution to soldering a dribbling pipe.
It seams logical, but I wanted to check if anyone has tried this, and if they had any problems getting the bread out.
Or is it a known urban myth?
Yes, us old-timers have used this trick for decades. My father showed it to me in the 1980s. I did just a few months ago when swapping a water heater. The idea is that you plug the pipe with a gob of bread, do your repair as the bread blocks and absorbs the trickle of water, and later it softens and dissolves, flowing down the pipe. You want to use just the inner part of plain white bread--no crust, seeds, etc. that can cause clogs elsewhere.
Just take into consideration where the bread muck will end up. If you're upstream of delicate equipment, such as a reverse osmosis system, it may not be a good idea. If you can flush it out fully later, have at it.
I'll add that I consider this a last-resort strategy. It can be difficult to make it work, especially with vertical pipes. Try fully venting the system and using a wet-dry vac first.
Isherwood is right and I have a long-time plumber that uses this method, possibly too much because he simply likes the idea. There is nothing wrong with this.
However... I will offer a more friendly DIY option for users who are not expert sodderers (yes know its not a word, should be).
Welding a dribbling pipe closed is not easy. There is a good amount of expertise. Also this will always be a failure point for the pipe after it is fixed.
For the DIYer... just add a sharkbite connector that you need like the ones below. They install with a dribble just fine.
If you are hiring a plumber they are removing that section, adding a connector on each end new copper in the middle. I do not let plumbers sodder pinhole or bad connections on my lines.
If you can't get the bread trick to work you could freeze the piping with dry ice. I have used dry ice many times but you have to be careful with the handling of it. If you have never used dry ice, see if anyone in your area has used it and will give you assistance. If all else fails you could contact a plumber that has a "pro press" machine to repair the drip for you.