Fix attemptd assignment to non-variable in bash 3 (#628)

* Fix attemptd assignment to non-variable in bash 3

flaghash variable is an associative array which is only supported in
bash > 3.

* Use -gt instead of >

bash_completions.go

@@ -175,6 +175,8 @@ __handle_flag()
     fi
 
     # keep flag value with flagname as flaghash
+    # flaghash variable is an associative array which is only supported in bash > 3.
+    if [[ -z "${BASH_VERSION}" || "${BASH_VERSINFO[0]}" -gt 3 ]]; then
         if [ -n "${flagvalue}" ] ; then
             flaghash[${flagname}]=${flagvalue}
         elif [ -n "${words[ $((c+1)) ]}" ] ; then
@@ -182,6 +184,7 @@ __handle_flag()
         else
             flaghash[${flagname}]="true" # pad "true" for bool flag
         fi
+    fi
 
     # skip the argument to a two word flag
     if __contains_word "${words[c]}" "${two_word_flags[@]}"; then