Accommodate systems where paths inherit their group from the parent dir.

Thanks to Thomas Klausner <tk@giga.or.at> for reporting the problem
and helping test the solution.

Signed-off-by: Rob Browning <rlb@defaultvalue.org>
Revert "Makefile: avoid using -Werror with clang for now."

Remove the clang -Werror special case after changing the way we handle
integer conversions (9ecba738e119654b7231be08232f8c484f8b1a93).

This reverts commit 3fdd538a22eae6681df3a59c116f78c237c9ecc7.

Thanks to Thomas Klausner <tk@giga.or.at> for the report.
README.md: change python-dev to python-devel for CentOS.

Thanks to Gao Yongwei <itxx00@gmail.com> for the report.

Signed-off-by: Rob Browning <rlb@defaultvalue.org>
test.sh: accommodate platforms where root defaults to "ls -A" again.

For now just use "bup ls -a" and "ls -A", which currently match in
behavior.  Of course we'll have to change that to "bup ls -A" once we
fix "bup ls".

Thanks to Thomas Klausner <tk@giga.or.at> for the report.

Signed-off-by: Rob Browning <rlb@defaultvalue.org>
Don't crash; defer an error when a path changes while indexing it.

Mirror the error handling already used by save.

With this change the result for a path that changes or is deleted
between the drecurse traversal and the from_path() call should be the
same as the result for a path that changes or is deleted between index
and save.

Thanks to Yann Autissier <yann.autissier@gmail.com> for reporting the
problem and Gabriel Filion <gabster@lelutin.ca> for helping figure out
the solution.

Signed-off-by: Rob Browning <rlb@defaultvalue.org>