Regression from 9.3 to 9.3.6: newlines getting swallowed on org-capture

[Kevin Liu]

This old thread describes similar behavior: 
https://emacs.stackexchange.com/questions/37097/newlines-swallowed-by-org-capture

Basically, the last position in the narrowed org-capture is actually the first 
position on the next line, so when you go to (end-of-buffer) and start typing 
you start clobbering the next headline.

I tested this with emacs -Q, capturing an `entry` with `file+headline` in org 
9.3 and it was working as expected, then in that same session loaded 9.3.6 and 
the capture buffer was one character longer (the added newline at the end) 
enabling the clobbering behavior.