Using either 'yes', 'no' or 'whatever', the user will be able to choose
whether to force block sequence items to be indented, to force them not
to be indented, or don't care, respectively.
Previously only comments that were indented like the following content
line were allowed, e.g.:
prev: line:
# commented line
current: line
With this change, such new cases are also allowed:
prev: line
# commented line 1
# commented line 2
current: line
`yaml.load()` exceptions are not necessarily syntax errors. For
instance, the following YAML source cannot be `load()`ed into a Python
object, but is valid nonetheless:
? - Detroit Tigers
- Chicago cubs
:
- 2001-07-23
? [ New York Yankees,
Atlanta Braves ]
: [ 2001-07-02, 2001-08-12,
2001-08-14 ]
This commit detects syntax errors from `yaml.parse()` exceptions rather
than `yaml.load_all()`.
