Merge pull request bitcoin#549 from jameshilliard/bip91-clarify

Clarify when BIP91 will cease to be active

Author: luke-jr

bip-0091.mediawiki

@@ -34,7 +34,7 @@ While this BIP is active, all blocks must set the nVersion header top 3 bits to
 
 This BIP will be deployed by a "version bits" with an 80%(this can be adjusted if desired) 269 block activation threshold and 336 block confirmation window BIP9 with the name "segsignal" and using bit 4.
 
-This BIP will have a start time of midnight June 1st, 2017 (epoch time 1496275200) and timeout on midnight November 15th 2017 (epoch time 1510704000). This BIP will cease to be active when segwit is locked-in.
+This BIP will have a start time of midnight June 1st, 2017 (epoch time 1496275200) and timeout on midnight November 15th 2017 (epoch time 1510704000). This BIP will cease to be active when segwit (BIP141) is locked-in, active, or failed
 
 === Reference implementation ===