rust-cpython: prepare for writing tests that require libpython
What I wanted is to disable the "cpython/extension-module<ver>" feature
while building tests executable, but that seems not doable. Instead,
this patch adds new features dedicated for tests.
The make rule is extracted so that we can easily run cargo tests.
Added a minimal test of ref-sharing as an example. More tests will follow.
#require execbit
$ hg init
$ echo a > a
$ hg ci -Am'not executable'
adding a
$ chmod +x a
$ hg ci -m'executable'
$ hg id
79abf14474dc tip
Make sure we notice the change of mode if the cached size == -1:
$ hg rm a
$ hg revert -r 0 a
$ hg debugstate
n 0 -1 unset a
$ hg status
M a
$ hg up 0
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg id
d69afc33ff8a
$ test -x a && echo executable -- bad || echo not executable -- good
not executable -- good