py3: convert a map expression into list comprehension

map returns a map object on Python 3 and here we wanted a list instead.

Differential Revision: https://phab.mercurial-scm.org/D2456

mercurial/crecord.py

@@ -547,7 +547,7 b' def testchunkselector(testfn, ui, header'
     chunkselector = curseschunkselector(headerlist, ui, operation)
     if testfn and os.path.exists(testfn):
         testf = open(testfn)
-        testcommands = map(lambda x: x.rstrip('\n'), testf.readlines())
+        testcommands = [x.rstrip('\n') for x in testf.readlines()]
         testf.close()
         while True:
             if chunkselector.handlekeypressed(testcommands.pop(0), test=True):