m_RenderingPath = 3: Upgrading to Unity 5.4

We've entered our end-of-year project at AIE, where we form up into teams consisting of programmers, artists and designers and are given 15 to make a game.

Last week, all computers in the campus had unity upgraded from unity 5.3.x to 5.4.  The upgrade of our project was relatively pain-free, but I did suffer a major problem when I pulled the project up at home, on my Linux machine.  Specifically, adjusting the view-port of a camera (i.e. for split-screen multi-player) no longer worked properly.  It just expanded the now smaller view-port to take up the whole of the game view. |:-/

After a Google search revealed nothing, I was preparing to submit a bug report, by starting a new project, when I noted that the new project did not exhibit the bug.  :?  After a lot of testing, I eventually narrowed the bug down to a single line in "ProjectSettings/ProjectSettings.asset":

m_RenderingPath: 3

3 was the value in my legacy project, while the new project had the value of 1.  I changed the value in our project to:

m_RenderingPath: 1

And the bug was gone.  Curiously,  a friend of mine in a similar position was having trouble with frame rate on their game (Windows10), and on a whim, I suggested this change, which resulted in almost doubling of the frame rate.

Update

It turns out that "m_RenderingPath" refers to the rendering pipeline that is used (i.e. Forward rendering, or deferred rendering).  "1" equates to forward rendering, and "3" equates to deferred rendering, so what has happened, is that deferred rendering was enabled at some point in the project, and was subsequently broken in the 5.4 update.