Comment # 15 on bug 936842 from Federico Mena Quintero

Note to self: look at upstream commit 701b7ab34984b0f9f0c357b0ff8b53c5132c6324
- that's the removal of the KeepTTY error, but there are commits close by that
fiddle with TTYs.

Stefan, could you please take a quick look at commit
6b79f28f5cb259f2168ecc3034fe2161e969bf7d which happened right after that one? 
I don't understand the implications of "Don't detach from controlling tty when
it is our vt" - I'm not sure if we need that commit in addition to the one that
removes the KeepTTY error.