stg clean removes conflicting patch

Hello!

If "stg push" fails, the subsequent "stg clean" will remove the patch
that could not been applied.  I think it's wrong.  Especially when doing
"stg pull", it can happen that I want to run "stg clean" to get rid of
the patches applied upstream so I can concentrate on the conflict.
Instead, the conflicting patch is removed too.

I've made a patch for the testsuite that should pass once the bug is
fixed.  Try removing "stg clean" from the test. and it will pass.  But
"stg clean" should make no difference here.

Add test to ensure that "stg clean" preserves conflicting patches

From: Pavel Roskin <redacted>

Signed-off-by: Pavel Roskin <redacted>
---

 t/t2500-clean.sh |   17 +++++++++++++++++
 1 files changed, 17 insertions(+), 0 deletions(-)

diff --git a/t/t2500-clean.sh b/t/t2500-clean.sh
index 3364c18..ad8f892 100755
--- a/t/t2500-clean.sh
+++ b/t/t2500-clean.sh

@@ -24,4 +24,21 @@ test_expect_success 'Clean empty patches' '
     [ "$(echo $(stg unapplied))" = "" ]
 '
 
+test_expect_success 'Create a conflict' '
+    stg new p1 -m p1 &&
+    echo bar > foo.txt &&
+    stg refresh &&
+    stg pop &&
+    stg new p2 -m p2
+    echo quux > foo.txt &&
+    stg refresh &&
+    ! stg push
+'
+
+test_expect_success 'Make sure conflicting patches are preserved' '
+    stg clean &&
+    [ "$(echo $(stg applied))" = "p0 p2 p1" ] &&
+    [ "$(echo $(stg unapplied))" = "" ]
+'
+
 test_done

-- 
Regards,
Pavel Roskin