demandimport: import sub-module relatively as expected (issue5208)
Before this patch, importing sub-module might (1) fail or (2) success
but import incorrect module, because demandimport tries to import
sub-module with level=-1 (on Python 2.x) or level=0 (on Python 3.x),
which is default value of "level" argument at construction of
"_demandmod" proxy object.
(1) on Python 3.x, importing sub-module always fails to import
existing sub-module
(2) both on Python 2.x and 3.x, importing sub-module might import
same name module on root level unintentionally
On Python 2.x, existing sub-module is prior to this unexpected
module. Therefore, this problem hasn't appeared.
To import sub-module relatively as expected, this patch specifies "1"
as import level explicitly at construction of "_demandmod" proxy
object for sub-module.
$ hg init
$ touch unknown
$ touch a
$ hg add a
$ hg ci -m "1"
$ touch b
$ hg add b
$ hg ci -m "2"
Should show unknown
$ hg status
? unknown
$ hg revert -r 0 --all
removing b
Should show unknown and b removed
$ hg status
R b
? unknown
Should show a and unknown
$ ls
a
unknown