set lower bound of directory to 1.2.7.1 (#542)

dhall.cabal

@@ -178,7 +178,7 @@ Library
         contravariant                              < 1.6 ,
         cryptonite                  >= 0.23     && < 1.0 ,
         Diff                        >= 0.2      && < 0.4 ,
-        directory                   >= 1.3      && < 1.4 ,
+        directory                   >= 1.2.7.1  && < 1.4 ,
         exceptions                  >= 0.8.3    && < 0.11,
         filepath                    >= 1.4      && < 1.5 ,
         haskeline                   >= 0.7.3.0  && < 0.8 ,
@@ -302,7 +302,7 @@ Benchmark dhall-parser
         containers                >= 0.5.0.0  && < 0.6,
         criterion                 >= 1.1      && < 1.6,
         dhall                                         ,
-        directory                 >= 1.3      && < 1.4,
+        directory                 >= 1.2.7.1  && < 1.4,
         serialise                                     ,
         text                      >= 0.11.1.0 && < 1.3
     Default-Language: Haskell2010

stack-lts-6.yaml

@@ -13,7 +13,7 @@ extra-deps:
 - basement-0.0.6
 - prettyprinter-1.2.0.1
 - prettyprinter-ansi-terminal-1.1.1.2
-- directory-1.3.1.0
+- directory-1.2.7.1
 - foundation-0.0.19
 - process-1.6.2.0
 - repline-0.1.7.0