# HG changeset patch
# User Gregory Szorc <gregory.szorc@gmail.com>
# Date 1512094786 18000
# Node ID 6614cac550aea66d19c601e45efd1b7bd08d7c40
# Parent  6169d95dce3becc4fb9ba50333fe4135dc426781
filelog: don't crash on invalid copy metadata (issue5748)

"copy" and "copyrev" are both supposed to appear next to each other.
However, a user report demonstrated a crash that indicates that
something in the wild is producing "copy" without "copyrev"
(probably `hg convert`).

While we should definitely fix the source of the bad metadata,
the bad code causing the crash is already in the wild and who knows
how many repositories are impacted. So let's be more defensive
when accessing the file revision metadata.

diff -r 6169d95dce3b -r 6614cac550ae mercurial/filelog.py
--- a/mercurial/filelog.py	Mon Apr 30 15:32:11 2018 -0700
+++ b/mercurial/filelog.py	Thu Nov 30 21:19:46 2017 -0500
@@ -135,7 +135,9 @@
             return False
         t = self.revision(node)
         m = revlog.parsemeta(t)[0]
-        if m and "copy" in m:
+        # copy and copyrev occur in pairs. In rare cases due to bugs,
+        # one can occur without the other.
+        if m and "copy" in m and "copyrev" in m:
             return (m["copy"], revlog.bin(m["copyrev"]))
         return False