`cd` may fails for multiple reasons:
- mistake when editing `.gitconfig` manually
- previously existing workspace that have been removed
- ...

Currently, if `cd` fails, the `BulkOp` continue its execution ... in the
workspace defined in a higher directory that where the user, despite the
user specified a specific workspace (`-w`).

The user should be noticed of a failed `cd` (this is really not expected
for a valid configuration) and the operations should stop to not execute
something unexpected.

marked this pull request as ready for review

Get rid of poor `eval` syntax because they are vulnerable to command
injection, which may have unexpected side effects.

However, they enabled a useful feature: using environment variable
(*e.g.*, defined in a `.bashrc`) inside the `.gitconfig` to use dynamic
paths as  `bulk` workspaces.

As such, I keep this feature possible by using the Bash's ${!VAR}
syntax, which allows to get the value of one variable using the name of
a another variable. However, arbitrary command injection is not possible
anymore.

Pierre Ayoub added 6 commits