util: add optional path auditor argument to canonpath
The canonpath function will default to creating its own path auditor,
but in some cases it will be useful to use a specialized auditor,
e.g., one that wont abort if a path lies within a subrepository.
merging a and b to b
warning: conflicts during merge.
merging b failed!
0 files updated, 0 files merged, 0 files removed, 1 files unresolved
use 'hg resolve' to retry unresolved file merges