Command tests: include regular PATH...

...after directory with the test executable.
I want to see if this fixes the CI problem on Windows, which
may be due to problems finding a DLL.

test/Tests/Helpers.hs

@@ -89,12 +89,14 @@ setupEnvironment testExePath = do
   mldpath   <- Env.lookupEnv "LD_LIBRARY_PATH"
   mdyldpath <- Env.lookupEnv "DYLD_LIBRARY_PATH"
   mpdd <- Env.lookupEnv "pandoc_datadir"
+  mbpath <- Env.lookupEnv "PATH"
   -- Note that Cabal sets the pandoc_datadir environment variable
   -- to point to the source directory, since otherwise getDataFilename
   -- will look in the data directory into which pandoc will be installed
   -- (but has not yet been).  So when we spawn a new process with
   -- pandoc, we need to make sure this environment variable is set.
-  return $ ("PATH",takeDirectory testExePath) :
+  return $ ("PATH",takeDirectory testExePath <>
+                    maybe mempty (searchPathSeparator:) mbpath) :
            ("TMP",".") :
            ("LANG","en_US.UTF-8") :
            ("HOME", "./") :