Use FETCH_HEAD to know where to rebase to after pull.

[stgit] / t / t1800-import / stg-export

test patch
---

 foo.txt |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/foo.txt b/foo.txt
index ad01662..d3cd5b6 100644
--- a/foo.txt
+++ b/foo.txt
@@ -3,6 +3,7 @@ dobedim
 dobedum
 dobidam
 dobidim
+dabadadash
 dobidum
 dobodam
 dobodim
@@ -20,6 +21,7 @@ dabedam
 dabedim
 dabedum
 dabidam
+dadadadash
 dabidim
 dabidum
 dabodam