bitbake: fetch2/git: ignore comments in .gitattributes when detecting LFS

Fixes [YOCTO 15917]

When fetching a git repository the .gitattributes file is scanned, checking if LFS
support is required for the repository. This scan checks if the word "lfs" is present
in the file, however the used regex doesn't account for comments, which makes some
repositories[1] be to misidentified as requiring LFS support (which fails fetching, in case
lfs support isn't installed on the build host).

To avoid it, change the used regex to ignore lines starting with "#".

[1]: e.g. https://github.com/MicrochipTech/cryptoauthlib

(Bitbake rev: 7917a758fc328747116c7899e689171bd0efc883)

Signed-off-by: Gyorgy Sarvari <skandigraun@gmail.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/fetch2/git.py

@@ -829,7 +829,7 @@ class Git(FetchMethod):
         """
         Check if the repository has 'lfs' (large file) content
         """
-        cmd = "%s grep lfs %s:.gitattributes | wc -l" % (
+        cmd = "%s grep '^[^#].*lfs' %s:.gitattributes | wc -l" % (
             ud.basecmd, ud.revision)
 
         try: