Fix empty assignment, bare variables and read lint warning

Author: unixorn

bin/git-show-overwritten

@@ -29,7 +29,7 @@ abort() {
 while [ "$#" -gt 0 ]; do
   case "$1" in
   --color ) colorize=1 ;;
-  --no-color ) colorize= ;;
+  --no-color ) colorize='';;
   -h | --help )
     sed -ne '/^#/!q;s/.\{1,2\}//;1d;p' < "$0"
     exit 0
@@ -101,14 +101,16 @@ git diff "${base}...${head}" --diff-filter=DM --no-prefix -w -U0 | grep -v '^+'
   }
   END { print num_lines, name_length }
 ' | sort -n | {
+  # shellcheck disable=SC2162
   read num_lines name_length
   if [ "$num_lines" -eq 0 ]; then
     color 31 "Warning: " >&2
     echo "no changed/removed lines found in the $base...$head diff" >&2
   fi
 
+  # shellcheck disable=SC2162
   while IFS=$'\t' read time sha author msg; do
-    date -r $time "+%Y-%m-%d" | tr -d $'\n'
+    date -r "$time" "+%Y-%m-%d" | tr -d $'\n'
     printf ' '
     color 33 "${sha:0:7}"
     printf '  '