[dpaste] Allow test run with any working directory

plugins/dpaste/tests/test_dpaste.fish

@@ -1,9 +1,11 @@
 #!/usr/bin/env fish
 
+set -l script_dir (dirname (status -f))
+
 function suite_dpaste
   function setup
     set -g __dpaste_expires_choises
-    source ../dpaste.fish
+    source $script_dir/../dpaste.fish
     __dpaste_set_defaults
   end
 
@@ -21,6 +23,6 @@ function suite_dpaste
 end
 
 if not set -q tank_running
-  source (dirname (status -f))/helper.fish
+  source $script_dir/helper.fish
   tank_run
 end