"Merging blocks with identical properties" behaving awkwardly

[joaocunha]

CSSO 1.3.11 node v0.10.36

I don't know exactly what is going on, so I couldn't name the issue properly.

This snippet:

.foo {
  color: green;
}
.bar {
  color: green;
}
div, section, span, table {
  color: red;
}
table, td, th {
  color: red;
}

...provides this output (which is expected):

.foo,.bar{color:green}div,section,span,table,td,th{color:red}

---

But if I add a property, it doesn't merge .foo and .bar anymore:

.foo {
  color: green;
}
.bar {
  color: green;
}
div, section, span, table {
  background: green; /* adding a property here breaks the merging */
  color: red;
}
table, td, th {
  color: red;
}

...and if I remove the div selector:

.foo {
  color: green;
}
.bar {
  color: green;
}
/* div */ section, span, table {
  background: green; /* the property is still here, but it works now */
  color: red;
}
table, td, th {
  color: red;
}

...it merges in a very awkward way:

.foo,.bar{color:green}section,span{color:red}section,span,table{background:green}table,td,th{color:red}