The second call to assert_config_entry_on_init_bytype is cleaned up by
the main cleanup function, but that overwrites the first _repo. Make
sure that one doesn't leak.
This fixes git_index_add and git_index_append to behave more like
core git, preserving old filemode data in the index when adding
and/or appending with core.filemode = false.
This also has placeholder support for core.symlinks and
core.ignorecase, but those flags are not implemented (well,
symlinks has partial support for preserving mode information in
the same way that git does, but it isn't tested).
git_commit() and git_tag() no longer prettify the
message by default. This has to be taken care of
by the caller.
This has the nice side effect of putting the
caller in position to actually choose to strip
the comments or not.
There are three actual changes in this commit:
1. When the trailing newline of a file is removed in a diff, the
change will now be reported with `GIT_DIFF_LINE_DEL_EOFNL` passed
to the callback. Previously, the `ADD_EOFNL` constant was given
which was just an error in my understanding of when the various
circumstances arose. `GIT_DIFF_LINE_ADD_EOFNL` is deprecated and
should never be generated. A new newline is simply an `ADD`.
2. Rewrote the `diff_delta__merge_like_cgit` function that contains
the core logic of the `git_diff_merge` implementation. The new
version doesn't actually have significantly different behavior,
but the logic should be much more obvious, I think.
3. Fixed a bug in `git_diff_merge` where it freed a string pool
while some of the string data was still in use. This led to
`git_diff_print_patch` accessing memory that had been freed.
The rest of this commit contains improved documentation in `diff.h`
to make the behavior and the equivalencies with core git clearer,
and a bunch of new tests to cover the various cases, oh and a minor
simplification of `examples/diff.c`.
