.

wcfs/testprog/treegen.py

@@ -153,7 +153,7 @@ def Trees(zstor, r):
 
     tree = zctx.root['treegen/tree'] = XLOTree()
     at0 = commit('treegen/tree: init')
-    print("start @%s tree=%s" % (ashex(at0), ashex(tree._p_oid)))
+    xprint("start @%s tree=%s" % (ashex(at0), ashex(tree._p_oid)))
 
     while 1:
         treetxt = r.readline()
@@ -406,6 +406,12 @@ def cmd_trees(argv):
     Trees(zstor, sys.stdin)
 
 
+# xprint prints msg to stdout and flushes it.
+def xprint(msg):
+    print(msg)
+    sys.stdout.flush()
+
+
 cmdRegistry = {
     'allstructs':   cmd_allstructs,
     'trees':        cmd_trees,

wcfs/δbtail_test.go

@@ -86,7 +86,7 @@ func StartTreeGen(zurl string) (_ *TreeGen, err error) {
 		}
 		return nil, err
 	}
-	defer xerr.Context(&err, "invalid start %q")
+	defer xerr.Contextf(&err, "invalid start %q", start)
 
 	// start @<at> tree=<root>
 	startRe := regexp.MustCompile(`^start @([^ ]+) root=([^ ]+)$`)
@@ -103,6 +103,7 @@ func StartTreeGen(zurl string) (_ *TreeGen, err error) {
 		return nil, fmt.Errorf("root: %s", err)
 	}
 
+	fmt.Printf("XXX started @%s root=%s\n", tg.head, tg.treeRoot)
 	return tg, nil
 }