Fix TNS-6: fully remove ns from deps graph

The clojure.tools.namespace.dependency/remove-node fn removes a
namespace's :dependencies set from the graph (outgoing edges), but
does not remove that namespace from the :dependents set of other
namespaces (ingoing edges). If a namespace is removed and one of its
dependencies is changed at the same time, as commonly occurs when
switching branches, then the removed namespace is still in the
:dependents of the changed namespace when it is reloaded. As all the
of the dependents of a changed namespace are also reloaded, this
throws a missing namespace error.

The resolution is to use clojure.tools.namespace.depedency/remove-all
to remove both outgoing (:dependencies) and ingoing (:dependents)
edges in the dependency graph.

However, care must be taken when choosing the point of change, because
clojure.tools.namespace.track/add relies on the partial removal
behaviour of clojure.tools.namespace.track/remove-deps. It uses
remove-deps to wipe the dependencies of a node, and cannot know how to
re-insert dependents if lost. Therefore the point of change should be
in clojure.tools.namespace.track/remove.

Signed-off-by: Fogus <[email protected]>

Author: zalky

src/main/clojure/clojure/tools/namespace/track.cljc

@@ -96,7 +96,7 @@
          :or {load (), unload (), deps (dep/graph)}} tracker
         known (set (dep/nodes deps))
         removed-names (filter known names)
-        new-deps (remove-deps deps removed-names)
+        new-deps (reduce dep/remove-all deps removed-names)
         changed (affected-namespaces deps removed-names)]
     (assoc tracker
       ::deps new-deps