solver: allow names with only one provider to be autoselected regardless of priority

src/solver.c

@@ -671,11 +671,12 @@ static void select_package(struct apk_solver_state *ss, struct apk_name *name)
 			    (!p->pkg->ss.iif_triggered ||
 			     !p->pkg->ss.tag_ok))
 				continue;
-			/* Virtual packages without provider_priority cannot be autoselected */
+			/* Virtual packages without provider_priority cannot be autoselected,
+			 * unless there is only one provider */
 			if (p->version == &apk_null_blob &&
 			    p->pkg->name->auto_select_virtual == 0 &&
 			    p->pkg->name->ss.requirers == 0 &&
-			    p->pkg->provider_priority == 0)
+			    (p->pkg->provider_priority == 0 && name->providers->num > 1))
 				continue;
 			if (compare_providers(ss, p, &chosen) > 0)
 				chosen = *p;

test/provides.repo

@@ -82,7 +82,7 @@ P:conflicted-provider-b
 V:0.1
 S:1
 I:1
-p:conflicted-provider
+p:conflicted-provider conflicted-provider-2
 
 C:Q1EyN5AdpAOBJWKMR89ppC66ccccj=
 P:conflicted-dep
@@ -104,3 +104,10 @@ V:0.1
 S:1
 I:1
 p:self-provide
+
+C:Q1EyN5AdpAOBJWKMR89ppC66eeeej=
+P:conflicted-dep-2
+V:0.1
+S:1
+I:1
+D:conflicted-provider-2