[wic][PATCH 3/4] oe/path: canonicalize('') should return '' rather than the cwd

[Trevor Woerner <twoerner@gmail.com>]

canonicalize() splits its input on the separator and, for every token
that does not contain an unexpanded bitbake variable, appends
os.path.realpath(path). It never guarded against an empty token, and
os.path.realpath('') returns the current working directory. So
canonicalize('') and canonicalize(None) produced the cwd instead of an
empty result, and a stray separator such as 'a,,b' injected a spurious
cwd entry between the real paths.

Skip empty tokens alongside the '$' tokens the loop already skips, so
empty input canonicalizes to '' and redundant separators no longer
introduce phantom cwd entries.

AI-Generated: codex/claude-opus 4.8 (xhigh)
Signed-off-by: Trevor Woerner <twoerner@gmail.com>
---
 src/wic/oe/path.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/wic/oe/path.py b/src/wic/oe/path.py
index 13c52b363694..95bb9648fab6 100644
--- a/src/wic/oe/path.py
+++ b/src/wic/oe/path.py
@@ -355,7 +355,11 @@ def canonicalize(paths, sep=','):
     # prefixes in sting compares later on, where the slashes then are important.
     canonical_paths = []
     for path in (paths or '').split(sep):
-        if '$' not in path:
+        # Skip empty tokens as well as unexpanded bitbake variables: an
+        # empty path would otherwise reach os.path.realpath(''), which
+        # returns the current working directory, so canonicalize('') or
+        # canonicalize(None) would wrongly produce the cwd instead of ''.
+        if path and '$' not in path:
             trailing_slash = path.endswith('/') and '/' or ''
             canonical_paths.append(os.path.realpath(path) + trailing_slash)
 
-- 
2.50.0.173.g8b6f19ccfc3a