lib/bb/checksum: avoid exception on broken symlinks

If using OE's externalsrc with a source tree that is not tracked by git
and contains broken symlinks, you can receive "TypeError: unorderable
types: NoneType() < str()" within the file checksum code due to:

 checksums.sort(key=operator.itemgetter(1))

Don't add files with no checksum to the checksums list in order to avoid
this.

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 4 insertions, 2 deletions

diff --git a/lib/bb/checksum.py b/lib/bb/checksum.py
index be4ab6891..84289208f 100644
--- a/lib/bb/checksum.py
+++ b/lib/bb/checksum.py
@@ -120,13 +120,15 @@ class FileChecksumCache(MultiProcessCache):
                             checksums.extend(checksum_dir(f))
                     else:
                         checksum = checksum_file(f)
-                        checksums.append((f, checksum))
+                        if checksum:
+                            checksums.append((f, checksum))
             elif os.path.isdir(pth):
                 if not os.path.islink(pth):
                     checksums.extend(checksum_dir(pth))
             else:
                 checksum = checksum_file(pth)
-                checksums.append((pth, checksum))
+                if checksum:
+                    checksums.append((pth, checksum))
 
         checksums.sort(key=operator.itemgetter(1))
         return checksums