Mageia: 2019-0391 Moderate: Libgit2 Denial of Service Threat

libgit2 has been updated to version 0.28.4 to fix several security issues:
* A carefully constructed commit object with a very large number of parents may lead to potential out-of-bounds writes or potential denial of service.
* CVE-2019-1348: the fast-import stream command "feature export-marks=path" allows writing to arbitrary file paths. As libgit2 does not offer any interface for fast-import, it is not susceptible to this vulnerability.
* CVE-2019-1350: recursive clones may lead to arbitrary remote code executing due to improper quoting of command line arguments. As libgit2 uses libssh2, which does not require us to perform command line parsing, it is not susceptible to this vulnerability.
* CVE-2019-1387: it is possible to let a submodule's git directory point into a sibling's submodule directory, which may result in overwriting parts of the Git repository and thus lead to arbitrary command execution. As libgit2 doesn't provide any way to do submodule c...