Fix a bug in regex extracting fields to "extra"

Because regex is built using a template string, \s* is actually escaped
into s*, i.e. literal "s" appearing 0 or more times. In most cases this
would mean that output can have spacing slightly off. In extreme case,
when identifier starts with letter "s", this could this could lead to
identifier being stored incorrectly.

Also adjusted tests to be more strict and mock data to cover this case.

chrome/content/zotero/import/mendeley/mendeleyImport.js

@@ -1241,7 +1241,7 @@ Zotero_Import_Mendeley.prototype._makeCreator = function (creatorType, firstName
 Zotero_Import_Mendeley.prototype._addExtraField = function (extra, field, val) {
 	// Strip the field if it appears at the beginning of the value (to avoid "DOI: DOI: 10...")
 	if (typeof val == 'string') {
-		val = val.replace(new RegExp(`^${field}:\s*`, 'i'), "");
+		val = val.replace(new RegExp(`^${field}:\\s*`, 'i'), "");
 	}
 	extra = extra ? extra + '\n' : '';
 	if (field != 'arXiv') {

test/tests/data/mendeleyMock/items-simple.json

@@ -14,7 +14,7 @@
         "identifiers":
         {
             "doi": "10.1111",
-            "pmid": "11111111",
+            "pmid": "PMID:    11111111",
             "arxiv": "1111.2222"
         },
         "starred": false,

test/tests/mendeleyImportTest.js

@@ -174,8 +174,7 @@ describe('Zotero_Import_Mendeley', function () {
 
 			// identifiers
 			assert.equal(journal.getField('DOI'), '10.1111');
-			assert.include(journal.getField('extra'), 'PMID: 11111111');
-			assert.include(journal.getField('extra'), 'arXiv: 1111.2222');
+			assert.sameMembers(journal.getField('extra').split('\n'), ['PMID: 11111111', 'arXiv: 1111.2222']);
 
 			// attachment & annotations
 			assert.lengthOf(withpdf.getAttachments(), 1);