[PATCHv2 06/14] completion: don't disambiguate tags and branches

When the completion script has to list only tags or only branches, it uses the 'git for-each-ref' format 'refname:short', which makes sure that all listed tags and branches are unambiguous. However, disambiguating tags and branches in these cases is wrong, because:

  - __git_tags(), the helper function listing possible tagname
    arguments for 'git tag', lists an ambiguous tag
    'refs/tags/ambiguous' as 'tags/ambiguous'.  Its only consumer,
    'git tag' expects its tagname argument to be under 'refs/tags/',
    thus it interprets that abgiguous tag as
    'refs/tags/tags/ambiguous'.  Clearly wrong.

  - __git_heads() lists possible branchname arguments for 'git branch'
    and possible 'branch.<branchname>' configuration subsections.
    Both of these expect branchnames to be under 'refs/heads/' and
    misinterpret a disambiguated branchname like 'heads/ambiguous'.

Furthermore, disambiguation involves several stat() syscalls for each tag or branch, thus comes at a steep cost especially on Windows and/or when there are a lot of tags or branches to be listed.

Use the 'git for-each-ref' format 'refname:strip=2' instead of 'refname:short' to avoid harmful disambiguation of tags and branches in __git_tags() and __git_heads().

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
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 contrib/completion/git-completion.bash | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)