fix: cword calculation w/custom wordbreaks and trailing whitespace

cword calculation was done wrongly with custom wordbreaks, if there
was only trailing whitespace after the caret, i.e. no additional words.

Author: Vampire

bash_completion

@@ -433,16 +433,16 @@ __reassemble_comp_words_by_ref()
                 ((i == COMP_CWORD)) && printf -v "$3" %s "$j"
                 # Remove optional whitespace + word separator from line copy
                 line=${line#*"${COMP_WORDS[i]}"}
-                # Start new word if word separator in original line is
-                # followed by whitespace.
-                [[ $line == [[:blank:]]* ]] && ((j++))
                 # Indicate next word if available, else end *both* while and
                 # for loop
                 if ((i < ${#COMP_WORDS[@]} - 1)); then
                     ((i++))
                 else
                     break 2
                 fi
+                # Start new word if word separator in original line is
+                # followed by whitespace.
+                [[ $line == [[:blank:]]* ]] && ((j++))
             done
             # Append word to current word
             ref="$2[$j]"

test/t/unit/test_unit_get_cword.py

@@ -153,3 +153,12 @@ def test_24(self, bash):
             ]
         )
         assert got == 1
+
+    def test_25(self, bash):
+        """
+        a b c:| with trailing whitespace after the caret (no more words) and
+        with WORDBREAKS -= : should return c:
+        """
+        assert_bash_exec(bash, "add_comp_wordbreak_char :")
+        output = self._test(bash, "(a b c :)", 3, "a b c: ", 6, arg=":")
+        assert output == "c:"