Fix build with QuickCheck 2.10.

QuickCheck added an Arbitrary instance for CTime aka EpochTime. However,
while git-annex's instance disallowed times before the epoch, QuickCheck's
does not. So, rather than using its instance, convert from an Integer.

This commit was sponsored by Thomas Hochstein on Patreon.

CHANGELOG

@@ -1,3 +1,9 @@
+git-annex (6.20170521) UNRELEASED; urgency=medium
+
+  * Fix build with QuickCheck 2.10.
+
+ -- Joey Hess <id@joeyh.name>  Sat, 17 Jun 2017 13:02:24 -0400
+
 git-annex (6.20170520) unstable; urgency=medium
 
   * move --to=here moves from all reachable remotes to the local repository.

Key.hs

@@ -147,7 +147,7 @@ instance Arbitrary Key where
 		<$> (listOf1 $ elements $ ['A'..'Z'] ++ ['a'..'z'] ++ ['0'..'9'] ++ "-_\r\n \t")
 		<*> (parseKeyVariety <$> (listOf1 $ elements ['A'..'Z'])) -- BACKEND
 		<*> ((abs <$>) <$> arbitrary) -- size cannot be negative
-		<*> arbitrary
+		<*> ((abs . fromInteger <$>) <$> arbitrary) -- mtime cannot be negative
 		<*> ((abs <$>) <$> arbitrary) -- chunksize cannot be negative
 		<*> ((succ . abs <$>) <$> arbitrary) -- chunknum cannot be 0 or negative
 

Utility/InodeCache.hs

@@ -210,7 +210,8 @@ instance Arbitrary InodeCache where
 		let prim = InodeCachePrim
 			<$> arbitrary
 			<*> arbitrary
-			<*> arbitrary
+			-- timestamp cannot be negative
+			<*> (abs . fromInteger <$> arbitrary)
 		in InodeCache <$> prim
 
 #ifdef mingw32_HOST_OS

Utility/QuickCheck.hs

@@ -35,9 +35,6 @@ instance (Arbitrary v, Ord v) => Arbitrary (S.Set v) where
 instance Arbitrary POSIXTime where
 	arbitrary = fromInteger <$> nonNegative arbitrarySizedIntegral
 
-instance Arbitrary EpochTime where
-	arbitrary = fromInteger <$> nonNegative arbitrarySizedIntegral
-
 {- Pids are never negative, or 0. -}
 instance Arbitrary ProcessID where
 	arbitrary = arbitrarySizedBoundedIntegral `suchThat` (> 0)