Arch Linux

Description:

I've recently developed a Julia binding for libalpm[1] and I used the doc of libalpm and the python binding as reference design. However I've noticed that there are many cases where the document is incorrect. Two of the most important ones (there are other places where the doc is unclear but pyalpm seems to get it right)

1. The returned list of `alpm_trans_prepare` and `alpm_trans_commit` are not always of the same type. They can have different types depending on the error code returned. (As a result, for example, installing package that triggers a invalid arch error segfault pyalpm).
2. `alpm_pkg_get_deltas` returns a list of `alpm_delta_t` not a list of string. This shouldn't cause segfault but will make the return info useless.

Additional info:
* package version(s)
* config and/or log files etc.


Steps to reproduce:

[1] https://github.com/yuyichao/LibALPM.jl