correct isReferenceTo() for references to files (PY-1514)

python/src/com/jetbrains/python/psi/impl/PyReferenceImpl.java

@@ -291,6 +291,10 @@ public class PyReferenceImpl implements PsiReferenceEx, PsiPolyVariantReference
   }
 
   public boolean isReferenceTo(PsiElement element) {
+    if (element instanceof PsiFileSystemItem) {
+      // may be import via alias, so don't check if names match, do simple resolve check instead
+      return resolve() == element;
+    }
     if (element instanceof PsiNamedElement) {
       final String elementName = ((PsiNamedElement)element).getName();
       if ((Comparing.equal(myElement.getReferencedName(), elementName) || PyNames.INIT.equals(elementName)) && !haveQualifiers(element)) {

python/testData/findUsages/Imports.py

@@ -0,0 +1,3 @@
+import r<caret>e
+
+x = re.compile('')

python/testSrc/com/jetbrains/python/PyFindUsagesTest.java

@@ -59,6 +59,11 @@ public class PyFindUsagesTest extends PyLightFixtureTestCase {
     assertUsages(usages);
   }
 
+  public void testImports() {  // PY-1514
+    final Collection<UsageInfo> usages = myFixture.testFindUsages("findUsages/Imports.py");
+    assertUsages(usages, "import <caret>re", "<caret>re.compile");
+  }
+
   private void assertUsages(Collection<UsageInfo> usages, String... usageTexts) {
     assertEquals(usageTexts.length, usages.size());
     List<UsageInfo> sortedUsages = new ArrayList<UsageInfo>(usages);