test: end printed diff "hunks" with an empty string in test-context.py

So that the resulting diff is correct and does not include a spurious empty
line between lines "diff --git a/foo b/foo" and "--- a/foo".

tests/test-context.py

@@ -59,7 +59,7 b' print(ctxb.status(ctxa))'
 # test performing a diff on a memctx
 
 for d in ctxb.diff(ctxa, git=True):
-    print(d)
+    print(d, end='')
 
 # test safeness and correctness of "ctx.status()"
 print('= checking context.status():')

tests/test-context.py.out

@@ -4,13 +4,11 b' Latin-1 : Gr\xfcezi!'
 UTF-8   : Grüezi!
 <status modified=['foo'], added=[], removed=[], deleted=[], unknown=[], ignored=[], clean=[]>
 diff --git a/foo b/foo
-
 --- a/foo
 +++ b/foo
 @@ -1,1 +1,2 @@
  foo
 +bar
-
 = checking context.status():
 == checking workingctx.status:
 wctx._status=<status modified=['bar-m'], added=['bar-a'], removed=['bar-r'], deleted=[], unknown=[], ignored=[], clean=[]>