portindex: Reuse entry from same portdir only

If a port is moved from one directory to another, for example when the
category is changed, the port must be reindexed. Otherwise, PortIndex
still references the old portdir and any action on the port would fail
as the Portfile cannot be found.

src/port/portindex.tcl

@@ -120,24 +120,28 @@ proc pindex {portdir} {
             set mtime [file mtime $portfile]
             if {$oldmtime >= $mtime} {
                 lassign [_read_index $qname] name len line
-                _write_index $name $len $line
-                incr stats(skipped)
+                array set portinfo $line
 
-                if {[info exists ui_options(ports_debug)]} {
-                    puts "Reusing existing entry for $portdir"
-                }
+                # reuse entry if it was made from the same portdir
+                if {[info exists portinfo(portdir)] && $portinfo(portdir) eq $portdir} {
+                    _write_index $name $len $line
+                    incr stats(skipped)
+
+                    if {[info exists ui_options(ports_debug)]} {
+                        puts "Reusing existing entry for $portdir"
+                    }
+
+                    # also reuse the entries for its subports
+                    if {![info exists portinfo(subports)]} {
+                        return
+                    }
+                    foreach sub $portinfo(subports) {
+                        _write_index {*}[_read_index [string tolower $sub]]
+                        incr stats(skipped)
+                    }
 
-                # also reuse the entries for its subports
-                array set portinfo $line
-                if {![info exists portinfo(subports)]} {
                     return
                 }
-                foreach sub $portinfo(subports) {
-                    _write_index {*}[_read_index [string tolower $sub]]
-                    incr stats(skipped)
-                }
-
-                return
             }
         } catch {{*} eCode eMessage} {
             ui_warn "Failed to open old entry for ${portdir}, making a new one"