_CheckDirReference: log actual error before suggesting --force-sync

A recent backward incompatible change created confusion and loss of
productivity and highlighted the very limited amount of information
provided when repo sync fails; merely recommending to --force-sync
and blow-up git repos without any hint as to why. The addition of
this basic _error(...) call would have provided a clue and will in
the future.

BUG=Issue 232
TEST=simulate a breakage similar to the ones reported at
  https://groups.google.com/a/chromium.org/forum/#!topic/chromium-os-dev/2-0oCy_CX5s
  cd .repo/projects/src/third_party/libapps.git/
  file info; rm info; ln -s wronglink info
  cd -
  repo sync src/third_party/libapps/
  # error message now shows the failure

Change-Id: Idd2f177a096f1ad686caa8c67cb361d594ccaa57
1 file changed
tree: ee4b3071c42e75bbd4dd955b9b1535bc15e5cd0b
  1. docs/
  2. hooks/
  3. subcmds/
  4. tests/
  5. .flake8
  6. .gitattributes
  7. .gitignore
  8. .mailmap
  9. .project
  10. .pydevproject
  11. color.py
  12. command.py
  13. COPYING
  14. editor.py
  15. error.py
  16. git_command.py
  17. git_config.py
  18. git_refs.py
  19. git_ssh
  20. gitc_utils.py
  21. main.py
  22. manifest_xml.py
  23. pager.py
  24. progress.py
  25. project.py
  26. pyversion.py
  27. README.md
  28. repo
  29. SUBMITTING_PATCHES.md
  30. trace.py
  31. wrapper.py
README.md

repo

Repo is a tool built on top of Git. Repo helps manage many Git repositories, does the uploads to revision control systems, and automates parts of the development workflow. Repo is not meant to replace Git, only to make it easier to work with Git. The repo command is an executable Python script that you can put anywhere in your path.