[PATCH] ez: Fix 'trailers -F' used on a single commit

[Rob Herring <robh@kernel.org>]

Running 'b4 trailers -u -F <msgid>' on a single commit fails:

CRITICAL: Failed to convert range to patches: Could not run rev-list None~1..409ee53c38a1d9a60e76ffa92088cfad07cea850

The problem is the loop is exited after 1 iteration and prevcommit is never
set.

Signed-off-by: Rob Herring <robh@kernel.org>
---
I think a base commit option and/or use upstream tracking branch is needed
here. There's probably cases where one wants to apply trailers and they
are not the author.
---
 b4/ez.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/b4/ez.py b/b4/ez.py
index cf8759015f29..1a9abd642623 100644
--- a/b4/ez.py
+++ b/b4/ez.py
@@ -834,6 +834,8 @@ def update_trailers(cmdargs: argparse.Namespace) -> None:
                 break
             prevparent = parent
             prevcommit = commit
+        if prevcommit is None:
+            prevcommit = end
         start = f'{prevcommit}~1'
     else:
         logger.critical('CRITICAL: Please specify -F msgid to look up trailers from remote.')
-- 
2.39.2