Fix to allow one-character tags

Author: idodeclare

opengrok-indexer/src/main/java/org/opengrok/indexer/history/GitTagParser.java

@@ -51,7 +51,7 @@ class GitTagParser implements Executor.StreamHandler {
      * <p>d305482d0acf552ccd290d6133a52547b8da16be:1427209918:tag: 0.12.1.5:
      */
     private static final Pattern PRETTY_TAG_MATCHER =
-            Pattern.compile("tag:\\s+(\\S[^,:]+)(?:,\\s+|:)");
+            Pattern.compile("tag:\\s+(\\S[^,:]*)(?:,\\s+|:)");
 
     /**
      * Stores the externally provided set.

opengrok-indexer/src/test/java/org/opengrok/indexer/history/GitTagParserTest.java

@@ -230,4 +230,21 @@ public void shouldParseOpenGrokTagsLog() throws IOException {
         assertEquals("tags should equal", t2.tags, floor2.tags);
         assertEquals("hashes should equal", t2.hash, ((GitTagEntry) floor2).hash);
     }
+
+    @Test
+    public void shouldParseOneCharacterTags() throws IOException {
+        final String LOG =
+                "c6963a7ea2753672325502d342e653700be550a8:1377876557:tag: z:\n" +
+                "c23e82b612acd5e947c164114377578116f6d298:1163621273::";
+        final byte[] LOG_BYTES = LOG.getBytes(StandardCharsets.UTF_8);
+        ByteArrayInputStream bytesIn = new ByteArrayInputStream(LOG_BYTES);
+
+        TreeSet<TagEntry> tagList = new TreeSet<>();
+        GitTagParser parser = new GitTagParser(tagList);
+        parser.processStream(bytesIn);
+
+        // See comment about LF count in shouldParseOpenGrokTagsLog().
+        long countLF = LOG.chars().filter(ch -> ch == '\n').count();
+        assertEquals("size should == LF count", countLF, tagList.size());
+    }
 }