[PATCH x3] vcs_info git: $gitbranch when operating from detached heads

[Daniel Shahaf <d.s@xxxxxxxxxxxxxxxxxx>]

I ran into the third patch while reproducing PWS's report from 36717.

The patches are semantically independent, each touches a different
branch of the if-else chain.

Also available from:
    git fetch git://github.com/danielshahaf/zsh/ vcs_info-nonsymbolic

From 9fb02f01a958af9ab4369e65f8663b50ec131a10 Mon Sep 17 00:00:00 2001
From: Daniel Shahaf <d.s@xxxxxxxxxxxxxxxxxx>
Date: Wed, 30 Sep 2015 14:21:59 +0000
Subject: [PATCH 1/3] vcs_info git: Compute %b correctly when merging to
 detached heads.

The %b expando should be the hash prior to the merge.  The hash of the merge
result is available as the %i expando and via the gen-applied-string hook.
---
 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 8ecc7c7..312f17c 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 () {
 
     elif [[ -f "${gitdir}/MERGE_HEAD" ]] ; then
         gitbranch="$(${(z)gitsymref} 2> /dev/null)"
-        [[ -z ${gitbranch} ]] && gitbranch="$(< ${gitdir}/MERGE_HEAD)"
+        [[ -z ${gitbranch} ]] && gitbranch="$(< ${gitdir}/ORIG_HEAD)"
 
     elif [[ -d "${gitdir}/rebase-merge" ]] ; then
         gitbranch="$(< ${gitdir}/rebase-merge/head-name)"
-- 
2.1.4

From 1a98630697c3193c496940c2acf14202a7d5097e Mon Sep 17 00:00:00 2001
From: Daniel Shahaf <d.s@xxxxxxxxxxxxxxxxxx>
Date: Wed, 30 Sep 2015 14:21:59 +0000
Subject: [PATCH 2/3] vcs_info git: Compute %b correctly when rebasing detached
 heads.

This sets the %b expando to the hash of the before-the-merge HEAD, rather
than to the literal string "detached HEAD".  That hash is already available
via the gen-applied-string hook.
---
 Functions/VCS_Info/Backends/VCS_INFO_get_data_git | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Functions/VCS_Info/Backends/VCS_INFO_get_data_git b/Functions/VCS_Info/Backends/VCS_INFO_get_data_git
index 312f17c..0a2a8bc 100644
--- a/Functions/VCS_Info/Backends/VCS_INFO_get_data_git
+++ b/Functions/VCS_Info/Backends/VCS_INFO_get_data_git
@@ -94,6 +94,10 @@ VCS_INFO_git_getbranch () {
 
     elif [[ -d "${gitdir}/rebase-merge" ]] ; then
         gitbranch="$(< ${gitdir}/rebase-merge/head-name)"
+        if [[ $gitbranch == 'detached HEAD' ]]; then
+            # get a sha1
+            gitbranch="$(< ${gitdir}/rebase-merge/orig-head)"
+        fi
 
     elif [[ -d "${gitdir}/.dotest-merge" ]] ; then
         gitbranch="$(< ${gitdir}/.dotest-merge/head-name)"
-- 
2.1.4

From 47697fe326c1eb6d022db2a2b3425bf1bf5ffd85 Mon Sep 17 00:00:00 2001
From: Daniel Shahaf <d.s@xxxxxxxxxxxxxxxxxx>
Date: Wed, 30 Sep 2015 14:21:59 +0000
Subject: [PATCH 3/3] vcs_info git: Compute %b correctly when "git am"-ing onto
 detached heads.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Before this patch, $gitbranch would be set to empty, which caused
VCS_INFO_get_data_git to early out with a failure status¹, consequently
$vcs_info_msg_0_ would be empty.

¹ via the 'if [[ -z ]]' block around line 170.
---
 Functions/VCS_Info/Backends/VCS_INFO_get_data_git | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Functions/VCS_Info/Backends/VCS_INFO_get_data_git b/Functions/VCS_Info/Backends/VCS_INFO_get_data_git
index 0a2a8bc..8664d51 100644
--- a/Functions/VCS_Info/Backends/VCS_INFO_get_data_git
+++ b/Functions/VCS_Info/Backends/VCS_INFO_get_data_git
@@ -87,6 +87,7 @@ VCS_INFO_git_getbranch () {
         gitbranch="$(${(z)gitsymref} 2> /dev/null)"
         [[ -z ${gitbranch} ]] && [[ -r ${actiondir}/head-name ]] \
             && gitbranch="$(< ${actiondir}/head-name)"
+        [[ -z ${gitbranch} ]] && gitbranch="$(< ${gitdir}/ORIG_HEAD)"
 
     elif [[ -f "${gitdir}/MERGE_HEAD" ]] ; then
         gitbranch="$(${(z)gitsymref} 2> /dev/null)"
-- 
2.1.4