amend: rectify comment
Comment was ambiguous as there can be two parents of a changeset in mercurial.
This commit fixes the comment to clarify that the first parent is being
considered.
Test Plan:
ran the test suite
Differential Revision: https://phab.mercurial-scm.org/D595
# 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