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.
#require symlink
https://bz.mercurial-scm.org/1438
$ hg init
$ ln -s foo link
$ hg add link
$ hg ci -mbad link
$ hg rm link
$ hg ci -mok
$ hg diff -g -r 0:1 > bad.patch
$ hg up 0
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg import --no-commit bad.patch
applying bad.patch
$ hg status
R link
? bad.patch