Copied from upstream: http://bugs.icu-project.org/trac/changeset/39484/.

Fixes <http://bugs.gnu.org/26462> (crashes).

Paths and line endings have been adapted.

Index: icu/source/common/ulist.c
===================================================================
--- icu/source/common/ulist.c	(revision 39483)
+++ icu/source/common/ulist.c	(revision 39484)
@@ -30,5 +30,4 @@
     
     int32_t size;
-    int32_t currentIndex;
 };
 
@@ -52,5 +51,4 @@
     newList->tail = NULL;
     newList->size = 0;
-    newList->currentIndex = -1;
     
     return newList;
@@ -81,6 +79,7 @@
         p->next->previous = p->previous;
     }
-    list->curr = NULL;
-    list->currentIndex = 0;
+    if (p == list->curr) {
+        list->curr = p->next;
+    }
     --list->size;
     if (p->forceDelete) {
@@ -151,5 +150,4 @@
         list->head->previous = newItem;
         list->head = newItem;
-        list->currentIndex++;
     }
     
@@ -194,5 +192,4 @@
     curr = list->curr;
     list->curr = curr->next;
-    list->currentIndex++;
     
     return curr->data;
@@ -210,5 +207,4 @@
     if (list != NULL) {
         list->curr = list->head;
-        list->currentIndex = 0;
     }
 }
@@ -273,3 +269,2 @@
     return (UList *)(en->context);
 }
-
Index: icu/source/i18n/ucol_res.cpp
===================================================================
--- icu/source/i18n/ucol_res.cpp	(revision 39483)
+++ icu/source/i18n/ucol_res.cpp	(revision 39484)
@@ -681,4 +681,5 @@
     }
     memcpy(en, &defaultKeywordValues, sizeof(UEnumeration));
+    ulist_resetList(sink.values);  // Initialize the iterator.
     en->context = sink.values;
     sink.values = NULL;  // Avoid deletion in the sink destructor.
Index: icu/source/test/intltest/apicoll.cpp
===================================================================
--- icu/source/test/intltest/apicoll.cpp	(revision 39483)
+++ icu/source/test/intltest/apicoll.cpp	(revision 39484)
@@ -82,14 +82,7 @@
     col = Collator::createInstance(Locale::getEnglish(), success);
     if (U_FAILURE(success)){
-        errcheckln(success, "Default Collator creation failed. - %s", u_errorName(success));
-        return;
-    }
-
-    StringEnumeration* kwEnum = col->getKeywordValuesForLocale("", Locale::getEnglish(),true,success);
-    if (U_FAILURE(success)){
-        errcheckln(success, "Get Keyword Values for Locale failed. - %s", u_errorName(success));
-        return;
-    }
-    delete kwEnum;
+        errcheckln(success, "English Collator creation failed. - %s", u_errorName(success));
+        return;
+    }
 
     col->getVersion(versionArray);
@@ -230,4 +223,27 @@
     delete aFrCol;
     delete junk;
+}
+
+void CollationAPITest::TestKeywordValues() {
+    IcuTestErrorCode errorCode(*this, "TestKeywordValues");
+    LocalPointer<Collator> col(Collator::createInstance(Locale::getEnglish(), errorCode));
+    if (errorCode.logIfFailureAndReset("English Collator creation failed")) {
+        return;
+    }
+
+    LocalPointer<StringEnumeration> kwEnum(
+        col->getKeywordValuesForLocale("collation", Locale::getEnglish(), TRUE, errorCode));
+    if (errorCode.logIfFailureAndReset("Get Keyword Values for English Collator failed")) {
+        return;
+    }
+    assertTrue("expect at least one collation tailoring for English", kwEnum->count(errorCode) > 0);
+    const char *kw;
+    UBool hasStandard = FALSE;
+    while ((kw = kwEnum->next(NULL, errorCode)) != NULL) {
+        if (strcmp(kw, "standard") == 0) {
+            hasStandard = TRUE;
+        }
+    }
+    assertTrue("expect at least the 'standard' collation tailoring for English", hasStandard);
 }
 
@@ -2467,4 +2483,5 @@
     TESTCASE_AUTO_BEGIN;
     TESTCASE_AUTO(TestProperty);
+    TESTCASE_AUTO(TestKeywordValues);
     TESTCASE_AUTO(TestOperators);
     TESTCASE_AUTO(TestDuplicate);
Index: icu/source/test/intltest/apicoll.h
===================================================================
--- icu/source/test/intltest/apicoll.h	(revision 39483)
+++ icu/source/test/intltest/apicoll.h	(revision 39484)
@@ -36,4 +36,5 @@
      */
     void TestProperty(/* char* par */);
+    void TestKeywordValues();
 
     /**