fix test failure locking an unlocked not present file

In v5, that was not possible, but it is in v6, and so the test was failing.

Investigating, it turns out that locking was copying the pointer file
content to the annex object despite the content not being present. So,
add a check to prevent that.

Command/Lock.hs

@@ -46,7 +46,7 @@ startNew file key = ifM (isJust <$> isAnnexLink file)
 	)
   where
 	go (Just key')
-		| key' == key = cont False
+		| key' == key = error "content not present; cannot lock"
 		| otherwise = errorModified
 	go Nothing = 
 		ifM (isUnmodified key file) 

Test.hs

@@ -546,9 +546,11 @@ test_preferred_content = intmpclonerepo $ do
 
 test_lock :: Assertion
 test_lock = intmpclonerepoInDirect $ do
-	-- regression test: unlock of not present file should skip it
 	annexed_notpresent annexedfile
-	not <$> git_annex "unlock" [annexedfile] @? "unlock failed to fail with not present file"
+	ifM (unlockedFiles <$> getTestMode)
+		( not <$> git_annex "lock" [annexedfile] @? "lock failed to fail with not present file"
+		, not <$> git_annex "unlock" [annexedfile] @? "unlock failed to fail with not present file"
+		)
 	annexed_notpresent annexedfile
 
 	-- regression test: unlock of newly added, not committed file