bash: fix shellcheck errors (#889)

https://github.com/koalaman/shellcheck/wiki/SC2207
https://github.com/koalaman/shellcheck/wiki/SC2164

Author: rsteube

bash_completions.go

@@ -72,7 +72,9 @@ __%[1]s_handle_reply()
             else
                 allflags=("${flags[*]} ${two_word_flags[*]}")
             fi
-            COMPREPLY=( $(compgen -W "${allflags[*]}" -- "$cur") )
+            while IFS='' read -r c; do
+                COMPREPLY+=("$c")
+            done < <(compgen -W "${allflags[*]}" -- "$cur")
             if [[ $(type -t compopt) = "builtin" ]]; then
                 [[ "${COMPREPLY[0]}" == *= ]] || compopt +o nospace
             fi
@@ -122,10 +124,14 @@ __%[1]s_handle_reply()
     if [[ ${#must_have_one_flag[@]} -ne 0 ]]; then
         completions+=("${must_have_one_flag[@]}")
     fi
-    COMPREPLY=( $(compgen -W "${completions[*]}" -- "$cur") )
+    while IFS='' read -r c; do
+        COMPREPLY+=("$c")
+    done < <(compgen -W "${completions[*]}" -- "$cur")
 
     if [[ ${#COMPREPLY[@]} -eq 0 && ${#noun_aliases[@]} -gt 0 && ${#must_have_one_noun[@]} -ne 0 ]]; then
-        COMPREPLY=( $(compgen -W "${noun_aliases[*]}" -- "$cur") )
+        while IFS='' read -r c; do
+            COMPREPLY+=("$c")
+        done < <(compgen -W "${noun_aliases[*]}" -- "$cur")
     fi
 
     if [[ ${#COMPREPLY[@]} -eq 0 ]]; then
@@ -160,7 +166,7 @@ __%[1]s_handle_filename_extension_flag()
 __%[1]s_handle_subdirs_in_dir_flag()
 {
     local dir="$1"
-    pushd "${dir}" >/dev/null 2>&1 && _filedir -d && popd >/dev/null 2>&1
+    pushd "${dir}" >/dev/null 2>&1 && _filedir -d && popd >/dev/null 2>&1 || return
 }
 
 __%[1]s_handle_flag()