Add a test for the 'P' command and fix current implementation so it

doesnt permanently modify the pattern space.

editors/sed.c

@@ -857,7 +857,11 @@ static void process_file(FILE * file)
 
 					if (tmp) {
 						*tmp = '\0';
+						puts(pattern_space);
+						*tmp = '\n';
+						break;
 					}
+					/* Fall Through */
 				}
 				case 'p':	/* Write the current pattern space to output */
 					puts(pattern_space);

testsuite/sed/sed-write-to-stdout

@@ -0,0 +1,10 @@
+busybox sed -n 'N;P;p'>output <<EOF
+a
+b
+c
+EOF
+cmp -s output - <<EOF
+a
+a
+b
+EOF