How to rewrite common prefix as header?

Say you're having a list of change notes like this:

2011-02-21: Removed first feature to get rid of previous customer
2011-02-21: Added second feature to open up new markets
2011-02-09: Implemented hot fix to calm down angry customer
2011-02-08: Developed project into a minimal viable product
2011-02-08: Started project

Can this be rewritten into the following format using standard shell tools?

2011-02-21
  * Removed first feature to get rid of previous customer
  * Added second feature to open up new markets

2011-02-09
  * Implemented hot fix to calm down a开发者_StackOverflowngry customer

2011-02-08
  * Developed project into a minimal viable product
  * Started project

If so, how?

Pipe through this.

#!/bin/bash

lastprefix=""
while read prefix line
do
  if [ "$prefix" != "$lastprefix" ]
  then
    lastprefix="$prefix";
    echo ""
    echo "$prefix"
  fi
  echo "  *  $line"
done

This should do it:

awk -F: '$1 != prev {print $1; prev = $1} {$1 = ""; print "  *" $0}' inputfile