Please see git-fetch(1) below -t, --tags Most of the tags are fetched automatically as branch heads are downloaded, but tags that do not point at objects reachable from the branch heads that are being tracked will not be fetched by this mechanism. This flag lets all tags and their associated objects be downloaded. Thus, if a user doesn't update their git repository for some weeks or months and then updating the repository may sometime cause "missing tags" If a ebuild developer specify such "missing tag" as EGIT_COMMIT, git_src_unpack fail to obtain the source files. Reproducible: Always
Fixed in git-2.eclass git.eclass is obsoleted by it so just migrate your ebuilds.