Fix incomplete dependencies with follow-all-variants

When `-dep-follow-all-variants` option is enabled, dependency resolving
process shouldn't stop even if dependency is already satisfied - there
mgiht be other ways to satisfy dependency.

Also fix issue with parsing multiarch specs like
`python:any`.

deb/list.go

@@ -124,6 +124,14 @@ func NewPackageListFromRefList(reflist *PackageRefList, collection *PackageColle
 	return result, nil
 }
 
+// Has checks whether package is already in the list
+func (l *PackageList) Has(p *Package) bool {
+	key := l.keyFunc(p)
+	_, ok := l.packages[key]
+
+	return ok
+}
+
 // Add appends package to package list, additionally checking for uniqueness
 func (l *PackageList) Add(p *Package) error {
 	key := l.keyFunc(p)
@@ -511,15 +519,27 @@ func (l *PackageList) FilterWithProgress(queries []PackageQuery, withDependencie
 
 			// try to satisfy dependencies
 			for _, dep := range missing {
-				// dependency might have already been satisfied
-				// with packages already been added
-				if result.Search(dep, false) != nil {
-					continue
+				if dependencyOptions&DepFollowAllVariants == 0 {
+					// dependency might have already been satisfied
+					// with packages already been added
+					//
+					// when follow-all-variants is enabled, we need to try to expand anyway,
+					// as even if dependency is satisfied now, there might be other ways to satisfy dependency
+					if result.Search(dep, false) != nil {
+						if dependencyOptions&DepVerboseResolve == DepVerboseResolve && progress != nil {
+							progress.ColoredPrintf("@{y}Already satisfied dependency@|: %s with %s", &dep, result.Search(dep, true))
+						}
+						continue
+					}
 				}
 
 				searchResults := l.Search(dep, true)
 				if len(searchResults) > 0 {
 					for _, p := range searchResults {
+						if result.Has(p) {
+							continue
+						}
+
 						if dependencyOptions&DepVerboseResolve == DepVerboseResolve && progress != nil {
 							progress.ColoredPrintf("@{g}Injecting package@|: %s", p)
 						}