sparse: clean up config signature code
Before, 0 was being used as the default signature value and we cast
the int to a string. We also handled I/O exceptions manually.
The new code uses cfs.tryread() so we always feed data into the
hasher. The empty string does hash and and should be suitable
for input into a cache key.
The changes made the code simple enough that the separate checksum
function could be inlined.
Mercurial
=========
Mercurial is a fast, easy to use, distributed revision control tool
for software developers.
Basic install:
$ make # see install targets
$ make install # do a system-wide install
$ hg debuginstall # sanity-check setup
$ hg # see help
Running without installing:
$ make local # build for inplace usage
$ ./hg --version # should show the latest version
See https://mercurial-scm.org/ for detailed installation
instructions, platform-specific notes, and Mercurial user information.