[PATCH] Get back to gbp buildpackage command to prepare gbp source

[Uladzimir Bely <ubely@ilbers.de>]

With removing stretch support we switched to `gbp export-orig` command
instead of `gbp buildpackage --git-ignore-new --git-builder=/bin/true`
one, since gbp versions in >= buster support this.

Unfortunately, this change makes other downstream layers change their
`GBP_EXTRA_OPTIONS` values in multiple recipes, e.g.:

`--git-(no-)pristine-tar` => `--(no-)pristine-tar`
`--git-upstream-branch=master` => `--upstream-branch=master`.

This creates too much inconvenience - we need to mention it in
RECIPE-API-CHANGELOG, use a different variable for `export-orig`
options, warn user if they still use old variable and, finally,
support both vars in Isar until all downstreams stop using old case.

It is not worth implementing all this stuff just for switching from
long 'buildpackage ...' to shorter 'export-orig ...' gbp subcommand

So, it's better to just revert a piece of "stretch removal" patch.

Signed-off-by: Uladzimir Bely <ubely@ilbers.de>
---
 meta/classes/dpkg-gbp.bbclass | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/meta/classes/dpkg-gbp.bbclass b/meta/classes/dpkg-gbp.bbclass
index f765eb9a..b1d7b240 100644
--- a/meta/classes/dpkg-gbp.bbclass
+++ b/meta/classes/dpkg-gbp.bbclass
@@ -9,13 +9,13 @@ S = "${WORKDIR}/git"
 
 PATCHTOOL ?= "git"
 
-GBP_EXTRA_OPTIONS ?= "--pristine-tar"
+GBP_EXTRA_OPTIONS ?= "--git-pristine-tar"
 
 SCHROOT_MOUNTS = "${WORKDIR}:${PP} ${GITDIR}:/home/.git-downloads"
 
 dpkg_runbuild_prepend() {
     sh -c "
         cd ${WORKDIR}/${PPS}
-        gbp export-orig ${GBP_EXTRA_OPTIONS}
+        gbp buildpackage --git-ignore-new --git-builder=/bin/true ${GBP_EXTRA_OPTIONS}
     "
 }
-- 
2.20.1

This replaces `Use GBP_EXPORT_ORIG_OPTIONS for dpg-gbp export command`
by switching to previous `gbp buildpackage` functionality.