tcsh can't search endif correctly if no space before "then"

Issue

• tcsh can't search endif correctly if no space before "then".
• Please refer to the following reproducer. After processing then-block(line 3) and finding else-statement(line 4), tcsh should jump to next line of the same level endif in line 9.
• However, tcsh fails to find proper endif(line 9) if space before then-statement in line 5 is omitted, then jumps to next line of endif in line 7.

Reproducer
     1  #!/bin/tcsh -f
     2  if (1 == 1) then
     3    echo 1
     4  else
     5    if (2 == 2)then  # <== no space before "then"
     6      echo 2
     7    endif
     8    echo "This message should not be shown"
     9  endif

Actual Result:
[root@rhel6 ~]# ./test.csh 
1
This message should not be shown
[root@rhel6 ~]#