*released Tue, 24 Jul 2018*
Minor bugfix, performance and compatibility release.
* Minor compatibility fix: on Linux, drop the use of the `attr` library,
and instead switch to the glibc header `sys/xattr.h`, which is
provided for a really long time (since glibc 2.3). The formerly used
header `attr/xattr.h` has been removed from the `attr` library in
version 2.4.48. Fix provided by Lars Wendler, many thanks!
* Release the GIL when performing I/O. Patch proposed by xwhuang, many
thanks. I tested this a long while back it seemed to impact
performance on local filesystems, but upon further inspection, the
downsides are minor (between 0 and 5%, in many cases negligible). For
remote or slow filesystems, this should allow much increased
parallelism.
* Fix symlink set operation on MacOS X; bugfix provided by adamlin, much
appreciated! This also uncovered testing problems related to symlinks,
which are now fixed (the bug would be caught by the updated tests).