record: fix up test issues

sed on BSD requires an arg to -i
sed failing exposed an uninitialized variable issue

hgext/record.py

@@ -324,6 +324,7 b' the hunk is left unchanged.'
 """)
                 (patchfd, patchfn) = tempfile.mkstemp(prefix="hg-editor-",
                         suffix=".diff", text=True)
+                ncpatchfp = None
                 try:
                     # Write the initial patch
                     f = os.fdopen(patchfd, "w")

tests/test-record.t

@@ -919,7 +919,7 b' Editing patch'
 
   $ cat > editor << '__EOF__'
   > #!/bin/sh
-  > sed -i -e 7d -e '5s/^-/ /' "$1"
+  > sed -i.bak -e 7d -e '5s/^-/ /' "$1"
   > __EOF__
   $ chmod +x editor
   $ cat > editedfile << '__EOF__'