alias-if-unalias-defun syntax error

[Kinnith Mark Wallace]

Configuration Information [Automatically generated, do not change]:
Machine: alphaev5
OS: osf5.1
Compiler: cc -I/usr/local/include
Compilation CFLAGS:  -DPROGRAM='bash' -DCONF_HOSTTYPE='alphaev5' 
-DCONF_OSTYPE='osf5.1' -DCONF_MACHTYPE='alphaev5-dec-osf5.1' 
-DCONF_VENDOR='dec' -DSHELL -DHAVE_CONFIG_H  -D_GNU_SOURCE  -I.  -I. 
-I./include -I./lib -I/usr/local/include -O -ieee -std1 -arch generic -tune ev67
uname output: OSF1 fly.hiwaay.net V5.1 1885 alpha
Machine Type: alphaev5-dec-osf5.1

Bash Version: 2.05
Patch Level: 8
Release Status: release

Description:
  A syntax error occurs when the following lines are input from
  command line or with 'source':
      alias gzip='command gzip -v'
      alias mygzip='command gzip'
      if true; then
        unalias mygzip
        mygzip() {
          gzip "$@"
        }
      fi
  However, a syntax error does NOT occur for the following variations
  (variation 3 has a different meaning than the original):
      # variation 1
      alias gzip='command gzip -v'
      alias mygzip='command gzip'
      unalias mygzip
      if true; then
        mygzip() {
          gzip "$@"
        }
      fi

      # variation 2
      alias gzip='command gzip -v'
      alias mygzip='command gzip'
      unalias mygzip
      mygzip() {
        gzip "$@"
      }

      # variation 3
      unalias gzip
      alias mygzip='gzip'
      if true; then
        unalias mygzip
        mygzip() {
          gzip "$@"
        }
      fi

Repeat-By:
  Input given lines from command line or with 'source'.