add benoit's test for issue148.

tests/test-pull-pull-corruption2

@@ -0,0 +1,24 b''
+#!/bin/sh
+#
+# Corrupt an hg repo with two pulls.
+#
+
+# create one repo with a long history
+hg init source1
+cd source1
+touch foo
+hg add foo
+for i in 1 2 3 4 5 6 7 8 9 10; do
+    echo $i >> foo
+    hg ci -m $i
+done
+cd ..
+
+# create a third repo to pull both other repos into it
+hg init version2
+hg -R version2 pull source1 &
+sleep 1
+
+hg clone --pull -U version2 corrupted
+hg -R corrupted verify
+hg -R version2 verify

tests/test-pull-pull-corruption2.out

@@ -0,0 +1,22 b''
+pulling from source1
+requesting all changes
+adding changesets
+adding manifests
+adding file changes
+added 10 changesets with 10 changes to 1 files
+(run 'hg update' to get a working copy)
+requesting all changes
+adding changesets
+adding manifests
+adding file changes
+added 10 changesets with 10 changes to 1 files
+checking changesets
+checking manifests
+crosschecking files in changesets and manifests
+checking files
+1 files, 10 changesets, 10 total revisions
+checking changesets
+checking manifests
+crosschecking files in changesets and manifests
+checking files
+1 files, 10 changesets, 10 total revisions