test-repair-strip: Don't rely on cat error message

tests/test-repair-strip

@@ -13,7 +13,11 teststrip() {
     chmod +$3 $4
     hg verify
     echo % journal contents
-    cat .hg/store/journal | sed 's/\.i[^\n]*/\.i/'
+    if [ -f .hg/store/journal ]; then
+        sed -e 's/\.i[^\n]*/\.i/' .hg/store/journal
+    else
+        echo "(no journal)"
+    fi
     ls .hg/store/journal >/dev/null 2>&1 && hg recover
     ls .hg/strip-backup/* >/dev/null 2>&1 && hg unbundle -q .hg/strip-backup/*
     rm -rf .hg/strip-backup

tests/test-repair-strip.out

@@ -46,7 +46,7 crosschecking files in changesets and ma
 checking files
 3 files, 4 changesets, 4 total revisions
 % journal contents
-cat: .hg/store/journal: No such file or directory
+(no journal)
 % before update 0, strip 2
 changeset:   0:cb9a9f314b8b
 user:        test