[PATCH v6 0/9] submodule: improve robustness of path handling

This series improves the robustness of path handling by 'git submodule' by:

* detecting submodule URLs that will result in non-sensical submodule origin URLs

* improving handling of various kinds of relative superproject origin URLs

* improving handling of various kinds of denormalized superproject origin URLs

This series differs from v5 in the following ways, by:

* Adding a more extensive set of failure tests to illustrate the conditions 
being addressed.

* Modifying the ../ processing loop in resolve_relative_url to exclude the 
'invariant' parts of absolute URLs from relative URL processing and thereby 
enable earlier and more accurate detection of edits that are going to 
produce a non-sensical output.

* Simplifying relative superproject origin URL support, by taking advantage of
the modifications above.

* Adding support for normalizing denormalized superproject origin URLs.

* Adding some additional regression tests to help guard against 
unintended regressions by this series.

* Improving the source code comments to better explain the purpose
of various code functions and code blocks

Jon Seymour (9):
  submodule: additional regression tests for relative URLs
  submodule: document failure to detect invalid submodule URLs
  submodule: document failure to handle relative superproject origin
    URLs
  submodule: document failure to handle improperly normalized remote
    origin URLs
  submodule: extract normalize_path into standalone function
  submodule: fix detection of invalid submodule URL
  submodule: fix sync handling of relative superproject origin URLs
  submodule: fix handling of denormalized superproject origin URLs
  submodule: fix normalization to handle repeated ./

 git-submodule.sh           | 118 +++++++++++++-----
 t/t7400-submodule-basic.sh | 297 ++++++++++++++++++++++++++++++++++++++++++++-
 t/t7403-submodule-sync.sh  |  84 ++++++++++++-
 3 files changed, 468 insertions(+), 31 deletions(-)