Strange parametrized modules vs inheritance behaviour in Erlang

a.erl

-module (a).
-compile (export_all).

hello () -> "Hello!".

a.erl_v2

-module (a, [X]).  %% a.erl with parameters
-compile (export_all).

hello () -> "Hello!".

b.erl

-module (b, [Info]).
-compile (export_all).
-extends (a).

info () -> Info.

does_not_work.log

$ erl
Erlang R15B02 (erts-5.9.2) [source] [64-bit] [smp:4:4] [async-threads:0] [kernel-poll:false]

Eshell V5.9.2  (abort with ^G)
1> 
1> 
1> a:module_info ().
[{exports,[{hello,0},{module_info,0},{module_info,1}]},
 {imports,[]},
 {attributes,[{vsn,[270635781666670138481523990332392551879]}]},
 {compile,[{options,[{outdir,"/home/hobby/test"}]},
           {version,"4.8.2"},
           {time,{2012,10,6,20,59,15}},
           {source,"/home/hobby/test/a.erl"}]}]
2> b:module_info ().
[{exports,[{new,1},
           {instance,2},
           {info,1},
           {module_info,0},
           {module_info,1}]},
 {imports,[]},
 {attributes,[{vsn,[54970594216433541512496372856475307087]},
              {abstract,[true]},
              {extends,[a]}]},
 {compile,[{options,[{outdir,"/home/hobby/test"}]},
           {version,"4.8.2"},
           {time,{2012,10,6,20,59,15}},
           {source,"/home/hobby/test/b.erl"}]}]
3> a:hello().
"Hello!"
4> b:new ("World").
** exception error: undefined function a:new/1
     in function  b:new/1 
5> q().
ok

modified_a.log

Erlang R15B02 (erts-5.9.2) [source] [64-bit] [smp:4:4] [async-threads:0] [kernel-poll:false]

Eshell V5.9.2  (abort with ^G)
1> b:new ("foo").
{b,{a,"foo"},"foo"}


...this (a.erl_v2) works, but it's very strange!!!

works_pretty_well.log

$ erl
Erlang R15B01 (erts-5.9.1) [source] [64-bit] [async-threads:0] [kernel-poll:false]

Eshell V5.9.1  (abort with ^G)
1> a:module_info ().
[{exports,[{hello,0},{module_info,0},{module_info,1}]},
 {imports,[]},
 {attributes,[{vsn,[270635781666670138481523990332392551879]}]},
 {compile,[{options,[{outdir,"/home/tmr/test"}]},
           {version,"4.8.1"},
           {time,{2012,10,6,20,55,42}},
           {source,"/home/tmr/test/a.erl"}]}]
2> b:module_info ().
[{exports,[{new,1},
           {instance,1},
           {info,1},
           {module_info,0},
           {module_info,1}]},
 {imports,[]},
 {attributes,[{vsn,[50133246433396715275574202450786346567]},
              {abstract,[true]},
              {extends,[a]}]},
 {compile,[{options,[{outdir,"/home/tmr/test"}]},
           {version,"4.8.1"},
           {time,{2012,10,6,20,55,42}},
           {source,"/home/tmr/test/b.erl"}]}]
3> a:hello().
"Hello!"
4> b:new ("World").
{b,"World"}
5> (b:new ("World")):info ().  
"World"
6> q().
ok