[PATCH 3/4] vcs_info git: During a non-interactive rebase of a detached head, computer the %b expando correctly.

[Daniel Shahaf <d.s@xxxxxxxxxxxxxxxxxx>]

Before this commit, the value of %b was the hash of the commit from the
"source" side of the rebase, from .git/rebase-apply/orig-head and
.git/rebase-apply/original-commit.  This broke the invariant that
%b expands to a git-rev-parse(1) expression resolving to what %r
expands to.

Use .git/rebase-apply/onto instead as, empirically, it contains the
correct value.
---
 Functions/VCS_Info/Backends/VCS_INFO_get_data_git | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Functions/VCS_Info/Backends/VCS_INFO_get_data_git b/Functions/VCS_Info/Backends/VCS_INFO_get_data_git
index cd57902b6..8305cf41a 100644
--- a/Functions/VCS_Info/Backends/VCS_INFO_get_data_git
+++ b/Functions/VCS_Info/Backends/VCS_INFO_get_data_git
@@ -90,7 +90,7 @@ VCS_INFO_git_getbranch () {
         [[ -z ${gitbranch} ]] && [[ -r ${actiondir}/head-name ]] \
             && gitbranch="$(< ${actiondir}/head-name)"
         [[ -z ${gitbranch} || ${gitbranch} == 'detached HEAD' ]] \
-            && gitbranch="$(< ${gitdir}/ORIG_HEAD)"
+            && gitbranch="$(< ${actiondir}/onto)"
 
     elif [[ -f "${gitdir}/MERGE_HEAD" ]] ; then
         gitbranch="$(${(z)gitsymref} 2> /dev/null)"