narrowspec: validate patterns when loading and saving spec file
Patterns should be normalized and validated before being passed into
narrowspec.save(). Let's assert that by checking immediately before
writing the narrow spec file. And let's assert that patterns loaded
from the spec file also conform.
Differential Revision: https://phab.mercurial-scm.org/D4524
# See http://EditorConfig.org for the specification
root = true
[*.py]
indent_size = 4
indent_style = space
trim_trailing_whitespace = true
[*.{c,h}]
indent_size = 8
indent_style = tab
trim_trailing_whitespace = true
[*.t]
indent_size = 2
indent_style = space
trim_trailing_whitespace = false