An is_*() named function should return true/false, but not modify things.
It has been renamed to a more adequate name: remove_path_slashes(char *).

Bug 4859

Previously, slashes '\' in job->cwd were always expanded regardless of they
were part of the name of a directory or not.

Bug 4859

When dealing with special characters like %A, %u, %s and so on and escaping it
on the command line, problems arises when one have directories with multiple
slashes in their names. This patch fixes this situation removing only one
slash on each pair of slashes just as normal escaping works i.e. in bash.

Bug 4859

Bug 5426.

Bug 5426.

Also remove some redundant logic

- avoid `abort()` when collective is failed
- added logging of coll details for fail cases

Bug 5067

- avoid `abort()` when collective is failed
- added logging of coll details for fail cases

Bug 5067

Note, this is setting it up so we can use defunct functions.  It will
probably need to be properly fixed in a future version so we don't
do this.