[QGIS-Developer] The left hand doesn't know what the right hand is doing

[Patrick Dunford]

With a recent change in masters the project file format has been broken 
yet again (it seems) and now instead of recognising EPSG:3857 on project 
files that are not very old, it comes up as USER:100029

Now ordinarily this wouldn't be an issue, just open project properties 
and change the CRS. Except there is a well documented bug that makes the 
software crash when you try to do this.

As it's not possible in any way for me to fix this latest inability to 
recognise the CRS from the previous project file from a slightly earlier 
version of master, maybe it would be helpful to document how we could 
actually insert the CRS into the project file by hand so it is correct.

thanks