Avoid creating an undefined start_phases entry when generating a release

When a release is generated and the applications in the release do not
define a value for the start_phases entry of their .app files, reltool
will generate the following entry in the .app files of the release:

{start_phases, undefined}

If this happens, when trying to create a release upgrade systools will
fail because it doesn't allow the start_phases entry to be set to
undefined. This patch avoids this situation by not generating a
start_phases entry when it is set to undefined.

1 files changed, 10 insertions, 6 deletions

diff --git a/lib/reltool/src/reltool_target.erl b/lib/reltool/src/reltool_target.erl
index 0fcf89a360..648978bd01 100644
--- a/lib/reltool/src/reltool_target.erl
+++ b/lib/reltool/src/reltool_target.erl
@@ -247,10 +247,15 @@ gen_app(#app{name = Name,
                               env = Env,
                               mod = StartMod,
                               start_phases = StartPhases}}) ->
-    StartMod2 =
-        case StartMod =:= undefined of
-            true  -> [];
-            false -> [{mod, StartMod}]
+    StartPhases2 =
+        case StartPhases of
+            undefined -> [];
+            _         -> [{start_phases, StartPhases}]
+        end,
+    Tail =
+        case StartMod of
+            undefined -> StartPhases2;
+            _         -> [{mod, StartMod} | StartPhases2]
         end,
     {application, Name,
      [{description, Desc},
@@ -261,10 +266,9 @@ gen_app(#app{name = Name,
       {applications, ReqApps},
       {included_applications, InclApps},
       {env, Env},
-      {start_phases, StartPhases},
       {maxT, MaxT},
       {maxP, MaxP} |
-      StartMod2]}.
+      Tail]}.
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %% Generate the contents of a rel file