[PATCHv2 0/5] Fix relative path issues in recursive submodules.

Thanks Junio, Eric and Jacob for review!

v2:
 * reworded commit message for test (Thanks Junio!)
 * instead of "simplifying" the path handling in patch 2, we are prepared
   for anything the user throws at us (i.e. instead of segfault we
       die(_("submodule--helper: unspecified or empty --path"));
   (Thanks Eric, Jacob for pushing back here!)
 * reword commit message for patch 3 (safe_create_leading_directories_const is
   not a check, Thanks Junio!)
 * patch 4 (the fix): That got reworked completely. No flow controlling
   conditions in the write out phase!
 * patch 5 is a bonus! (replace fprintf by fprintf_or die) When implementing
   that I wondered if we also have close_or_die and open_or_die, but that doesn't
   seem to be the case.
   
Thanks,
Stefan

v1:

It took me longer than expected to fix this bug.

It comes with a test and minor refactoring and applies on top of origin/sb/submodule-helper, such that it can be merged into 2.7, 2.8 as well as master.

Patch 1 is a test which fails; it has a similar layout as the real failing repository Norio Nomura pointed out, but simplified to the bare essentials for reproduction of the bug.

Patch 2&3 are not strictly necessary for fixing the isseu, but it removes stupid code I wrote, so the resulting code looks a little better.

Patch 4 fixes the issue by giving more information to relative_path, such that a relative path can be found in all cases.

Thanks, Stefan

Stefan Beller (5):
  recursive submodules: test for relative paths
  submodule--helper clone: simplify path check
  submodule--helper clone: remove double path checking
  submodule--helper, module_clone: always operate on absolute paths
  submodule--helper, module_clone: catch fprintf failure

 builtin/submodule--helper.c | 52 +++++++++++++++++++++++++--------------------
 t/t7400-submodule-basic.sh  | 41 +++++++++++++++++++++++++++++++++++
 2 files changed, 70 insertions(+), 23 deletions(-)