util: make copyfile avoid ambiguity of file stat if needed
In some cases below, copying from backup is used to restore original
contents of a file. If copying keeps ctime, mtime and size of a file,
restoring is overlooked, and old contents cached before restoring
isn't invalidated as expected.
- failure of transaction before closing (from '.hg/journal.backup.*')
- rollback of previous transaction (from '.hg/undo.backup.*')
To avoid such problem, this patch makes copyfile() avoid ambiguity of
file stat, if needed.
Ambiguity check is executed, only if:
- checkambig=True is specified (not all copying needs ambiguity check), and
- destination file exists before copying
This patch also adds 'not (copystat and checkambig)' assertion,
because combination of copystat and checkambig is meaningless.
This patch is a part of preparation for "Exact Cache Validation Plan":
https://www.mercurial-scm.org/wiki/ExactCacheValidationPlan
# 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