Bug #440 - Parser fails to simultaneously subst and append

- The code wasn't even trying to apply the substitutions for the
  append and prepend commands.

ChangeLog

@@ -39,6 +39,7 @@
  + Fixed bug #438, correcting the sorting of the entry_time, start_time
    and end_time columns (thanks to Michelle Crane).
  + Fixed bug #439, which ignored dateformat.annotation for sparse annotations.
+ + Fixed bug #440, which prevented simultaneous append/prepend and substitution.
  + Fixed bug #441, which misparsed '/a/a:/' as an attribute, rather than a
    substitution (thanks to Michelle Crane).
  + Fixed bug #444, which made task shell unusable after canceling out of an

src/command.cpp

@@ -1610,6 +1610,7 @@ int handleAppend (std::string &outs)
           changes += deltaAppend (*other);
           changes += deltaTags (*other);
           changes += deltaAttributes (*other);
+          changes += deltaSubstitutions (*other);
 
           if (taskDiff (before, *other))
           {
@@ -1686,6 +1687,7 @@ int handlePrepend (std::string &outs)
           changes += deltaPrepend (*other);
           changes += deltaTags (*other);
           changes += deltaAttributes (*other);
+          changes += deltaSubstitutions (*other);
 
           if (taskDiff (before, *other))
           {