1. Summarise the issue (what were doing, what went wrong?)

If we try to apply a patch which has dependencies that are missing, we
get an error listing the missing patches. If we try to get --context
with the same patchfile, we just get told that there are missing
patches, not what they are:

> darcs apply foopatch.dpatch

darcs failed:  Sun Sep  9 15:40:05 BST 2012  Ganesh Sittampalam
<ganesh@earth.li>
  tagged 2.9.5

FATAL: Cannot apply this bundle. We are missing the above patches.

> darcs get repo --context foopatch.dpatch

Copying patches, to get lazy repository hit ctrl-C...
Using lazy repository.                                      
darcs: Missing patches from context!

2. What behaviour were you expecting instead?

I want darcs to tell me which patches are missing when using darcs get
--context

3. What darcs version are you using? (Try: darcs --exact-version)

2.9.4 (+ 11 patches)

4. What operating system are you running?

Linux x86_64

Note that this bug is only about the error message shown - I just want
darcs get --context to fail with an error containing the missing
patches' names.

resolved by

patch 71465505ff2739ec188389590751f0d82ade6dc1
Author: Ben Franksen <ben.franksen@online.de>
Date:   Fri Aug  2 19:06:48 CEST 2019
  * turn an error call into a proper failure when cloning