diff CHANGELOG @ 4797:8c780c3eb116

evolve: fixed lock acquire before checking state

Before checking the states `repo.lock()` and `repo.wlock()` need
to be acquired. This was not happening in `evolve()` earlier.

This patch creates a seperate `_performevolve()` funtion which
can be then called with locks acquired.

This also removes the redundant lock acuquiring of `abortevolve`
and `continueevolve` as lock is now taken earlier.

--- a/CHANGELOG	Wed Jul 31 10:52:14 2019 -0700
+++ b/CHANGELOG	Fri Jul 12 23:43:25 2019 +0530
@@ -5,6 +5,7 @@
 -------------------
 
   * prune: clarify error message when no revision were passed,
+  * evolve: avoid possible race conditions bu locking earlier
 
 9.1.0 -- 2019-07-29
 -------------------