Getting a list of changed files between to different branches or tags could not be any easier when using the ‘–name-only’ diff option:

git diff --name-only mono-3.2.5 mono-3.2.6

configure.in
mcs/class/Facades/Makefile
mcs/class/Facades/System.Dynamic.Runtime/TypeForwarders.cs
mcs/class/Facades/System.Runtime.InteropServices.WindowsRuntime/AssemblyInfo.cs
mcs/class/Facades/System.Runtime.InteropServices.WindowsRuntime/Makefile
...

A quickie to get the number of files changed:

git diff --name-only mono-3.2.5 mono-3.2.6|wc -l
      28

And using the ‘–name-status’ option can get you a nice two column output with the change type attribute with each file name, makes it easy to pipe to those maintenace scripts.

git diff --name-status mono-3.2.5 mono-3.2.6
M       configure.in
M       mcs/class/Facades/Makefile
M       mcs/class/Facades/System.Dynamic.Runtime/TypeForwarders.cs
A       mcs/class/Facades/System.Runtime.InteropServices.WindowsRuntime/AssemblyInfo.cs

Note: You can feed the ‘–no-color’ option to make sure that none of those ansi escape codes get send down-stream in your pipe.

Note: ‘–'porcelain’ works within the diff mode sub-option but not as a primary option.