Before this change, running `docker context rm --force` would fail if the context
did not exist. This behavior was different from other commands, which allowed
ignoring non-existing objects.
For example; when trying to remove a non-existing volume, the command would
fail without "force":
```bash
docker volume rm nosuchvolume
Error: No such volume: nosuchvolume
echo $?
1
```
But using the `-f` / `--force` option would make the command complete successfully
(the error itself is still printed for informational purposes);
```bash
docker volume rm -f nosuchvolume
nosuchvolume
echo $?
0
```
With this patch, `docker context rm` behaves the same:
```bash
docker context rm nosuchcontext
context "nosuchcontext" does not exist
echo $?
1
```
```bash
docker context rm -f nosuchcontext
nosuchcontext
echo $?
0
```
This patch also simplifies how we check if the context exists; previously we
would try to read the context's metadata; this could fail if a context was
corrupted, or if an empty directory was present. This patch now only checks
if the directory exists, without first validating the context's data.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
9a493b1bf7