Ignore comment line from the .dockerignore file

This fixed the bug that test comment line in .dockerignore file as ignore rule
bug.

Add test for "# comment" patterns in .dockerignore.

Signed-off-by: Wanzhi Du <[email protected]>

Author: 0x11-dev

docker/api/build.py

@@ -143,7 +143,7 @@ def build(self, path=None, tag=None, quiet=False, fileobj=None,
             if os.path.exists(dockerignore):
                 with open(dockerignore, 'r') as f:
                     exclude = list(filter(
-                        bool, [l.strip() for l in f.read().splitlines()]
+                        lambda x: x != '' and x[0] != '#', [l.strip() for l in f.read().splitlines()]
                     ))
             context = utils.tar(
                 path, exclude=exclude, dockerfile=dockerfile, gzip=gzip

tests/integration/api_build_test.py

@@ -61,7 +61,8 @@ def test_build_with_dockerignore(self):
                 'Dockerfile',
                 '.dockerignore',
                 '!ignored/subdir/excepted-file',
-                '',  # empty line
+                '',  # empty line,
+                '#', # comment line
             ]))
 
         with open(os.path.join(base_dir, 'not-ignored'), 'w') as f: