Fix changelog for ticket 25614 to make it pass check-changes.

Yawning's commit in fda61e030e12cbd66a2be9905e6855ec6c6a3c63 was used to
find which version this is a bugfix on.

changes/ticket25614

@@ -1,3 +1,3 @@
   o Minor bugfixes (pluggable transports):
     - Tor now sets TOR_PT_EXIT_ON_STDIN_CLOSE=1 for client transports as
-      well as servers. Closes ticket 25614.
+      well as servers. Fixes bug 25614; bugfix on 0.2.7.1-alpha.