missing dependencies throw assertion errors instead of dependency solving error

[itziakos]

for example legacy

PS C:\Users\itziakos\Projects\haas> jaguar --no-debug install ipython-3.0.0-1
Fetching package repositories indices.. done
One of the requested package has broken dependencies
(Dependency solving error: Could not resolve "terminado 0.5" required by "RemotePackageMetadata('ipython-3.0.0-1', key='ipython-3.0.0-1.egg', available=True, product='free', repository_info='BroodRepository(<https://packages.enthought.com>, <enthought/free>)')")

while sat_solver

PS C:\Users\itziakos\Projects\haas> jaguar --no-debug install ipython-3.0.0-1
Fetching package repositories indices.. done
Unexpected error
AssertionError("No candidates found for requirement 'terminado', needed for dependency RepositoryPackageMetadata('ipython-3.0.0-1', repo=Repository(<enthought/free>))",)

[cournape]

We need to do 2 things here:

1. Better error handling in the SAT solver (that should not be too complicated)
2. Figure out what to do about broken dependencies when they are not explicitly required. In your case, we should fail with a message clear to the legacy case, but if all you want is one version of ipython, we should maybe just ignore packages with broken dependencies.