fix: stale pattern n.path after colon-encoding

Author: alandefreitas

src/detail/pattern.cpp

@@ -288,6 +288,7 @@ apply(
                         dest0++;
                     }
                 }
+                n.path += diff;
             }
         }
         // 2) url has no authority and path

test/unit/format.cpp

@@ -943,6 +943,17 @@ struct format_test
         }
     }
 
+    void
+    testColonInFirstSegment()
+    {
+        // first segment with colon triggers encoding;
+        // n.path must be updated after colon-encoding
+        {
+            url u = urls::format("{}", "a:b");
+            BOOST_TEST_CSTR_EQ(u.encoded_path(), "a%3Ab");
+        }
+    }
+
     void
     run()
     {
@@ -953,6 +964,7 @@ struct format_test
         testFormat();
         testLLONGMIN();
         testCenterAlignPad();
+        testColonInFirstSegment();
 #endif
     }
 };