smartlog: fix indentnonpublic when public rev is 0

Summary: Observed this bug when I was creating an example repo.

Reviewed By: sggutier

Differential Revision: D68914044

fbshipit-source-id: bf63fd5520e893325512655b98bce871d226c7c1

eden/scm/sapling/ext/smartlog.py

@@ -176,7 +176,7 @@ def unzip(parents):
                 if pctx.ispublic():
                     prev = results[i][0]
                     break
-            if prev:
+            if prev is not None:
                 reserved.append(prev)
 
     return results, reserved

eden/scm/tests/test-fb-ext-smartlog.t

@@ -404,3 +404,14 @@ Make sure public commits that are descendants of master are not drawn
   │
   ~
 
+Indent non-public when public rev is 0:
+
+  $ newrepo
+  $ echo 'A-B' | drawdag
+  $ sl debugmakepublic $A
+  $ sl dbsh -c "cl.inner.flush([bin('$A')])"  # reassign $A to "master group" so its rev is 0
+  $ sl smartlog -T '{rev} {desc} {phase}' --config smartlog.indentnonpublic=1
+    o  281474976710656 B draft
+  ╭─╯
+  o  0 A public
+