gps: Fix up odds and ends around IgnoreRulesets

The most crucial piece is fixing the hasher to make its prefix checks
without the wildcard suffix for the purpose of determining whether the
ignore affects the root project; otherwise, wildcards on the root of the
current project (why would you do this?) would be erroneously included
in hash inputs.

internal/gps/hash.go

@@ -85,7 +85,10 @@ func (s *solver) writeHashingInputs(w io.Writer) {
 	ig := s.rd.ir.ToSlice()
 	sort.Strings(ig)
 	for _, igp := range ig {
-		if !strings.HasPrefix(igp, s.rd.rpt.ImportRoot) || !isPathPrefixOrEqual(s.rd.rpt.ImportRoot, igp) {
+		// Typical prefix comparison checks will erroneously fail if the wildcard
+		// is present. Trim it off, if present.
+		tigp := strings.TrimSuffix(igp, "*")
+		if !strings.HasPrefix(tigp, s.rd.rpt.ImportRoot) || !isPathPrefixOrEqual(s.rd.rpt.ImportRoot, tigp) {
 			writeString(igp)
 		}
 	}

internal/gps/rootdata.go

@@ -20,12 +20,6 @@ type rootdata struct {
 	// Ruleset for ignored import paths.
 	ir *pkgtree.IgnoredRuleset
 
-	// Map of packages to ignore.
-	ig map[string]bool
-
-	// Radix tree of ignore prefixes.
-	igpfx *radix.Tree
-
 	// Map of packages to require.
 	req map[string]bool
 

internal/gps/solver.go

@@ -195,10 +195,7 @@ func (params SolveParameters) toRootdata() (rootdata, error) {
 		an:      params.ProjectAnalyzer,
 	}
 
-	// Ensure the required, ignore and overrides maps are at least initialized
-	if rd.ig == nil {
-		rd.ig = make(map[string]bool)
-	}
+	// Ensure the required and overrides maps are at least initialized
 	if rd.req == nil {
 		rd.req = make(map[string]bool)
 	}