qpkg/test/bug-adding: found another manifestation of the same problem

This time, we even fail an assertion. Once again, it's because the state
changes are out of sync with the "under consideration" stack.

qpkg/test/bug-adding

@@ -42,3 +42,57 @@ EOF
 expect <<EOF
 package C version 0 has cyclic dependency
 EOF
+
+###############################################################################
+
+#
+# We also fail (badly) to restore QPKG_ADDING after we moved on:
+#
+# A -> B, D
+# B -> C_1
+#      C_0 -> B
+# D conflicts with C_1
+#
+# "resolve" recurses as follows:
+#
+# A_0		-> B
+#   B_0|D	-> C
+#     C_1|D	-> next (we clear B here !)
+#       D_0	-> done
+#     C_0|D	-> next (we try to clear B again)
+#
+
+qpkg_fail "BUG: we don't restore QPKG_ADDING, missing errors" \
+  prereq A <<EOF
+Package: D
+Version: 0
+Architecture: test
+Filename: D
+
+Package: C
+Version: 1
+Architecture: test
+Filename: C_1
+
+Package: C
+Version: 0
+Architecture: test
+Depends: B
+Filename: C_0
+
+Package: B
+Version: 0
+Architecture: test
+Depends: C
+Filename: B
+
+Package: A
+Version: 0
+Architecture: test
+Depends: B, D
+Filename: A
+EOF
+expect <<EOF
+qpkg: prereq.c:185: resolve: Assertion \`top->pkg->flags & QPKG_ADDING' failed.
+Aborted
+EOF