fix: incomplete environment values merging (#378)

Fixes #377

Ref https://github.com/imdario/mergo/pull/81

vendor/github.com/imdario/mergo/README.md

@@ -27,7 +27,7 @@ It is ready for production use. [It is used in several projects by Docker, Googl
 
 ### Latest release
 
-[Release v0.3.4](https://github.com/imdario/mergo/releases/tag/v0.3.4).
+[Release v0.3.6](https://github.com/imdario/mergo/releases/tag/v0.3.6).
 
 ### Important note
 

vendor/github.com/imdario/mergo/merge.go

@@ -9,6 +9,7 @@
 package mergo
 
 import (
+	"fmt"
 	"reflect"
 )
 
@@ -103,7 +104,15 @@ func deepMerge(dst, src reflect.Value, visited map[uintptr]*visit, depth int, co
 				case reflect.Ptr:
 					fallthrough
 				case reflect.Map:
-					if err = deepMerge(dstElement, srcElement, visited, depth+1, config); err != nil {
+					srcMapElm := srcElement
+					dstMapElm := dstElement
+					if srcMapElm.CanInterface() {
+						srcMapElm = reflect.ValueOf(srcMapElm.Interface())
+						if dstMapElm.IsValid() {
+							dstMapElm = reflect.ValueOf(dstMapElm.Interface())
+						}
+					}
+					if err = deepMerge(dstMapElm, srcMapElm, visited, depth+1, config); err != nil {
 						return
 					}
 				case reflect.Slice:
@@ -116,7 +125,14 @@ func deepMerge(dst, src reflect.Value, visited map[uintptr]*visit, depth int, co
 						dstSlice = reflect.ValueOf(dstElement.Interface())
 					}
 
-					dstSlice = reflect.AppendSlice(dstSlice, srcSlice)
+					if !isEmptyValue(src) && (overwrite || isEmptyValue(dst)) && !config.AppendSlice {
+						dstSlice = srcSlice
+					} else if config.AppendSlice {
+						if srcSlice.Type() != dstSlice.Type() {
+							return fmt.Errorf("cannot append two slice with different type (%s, %s)", srcSlice.Type(), dstSlice.Type())
+						}
+						dstSlice = reflect.AppendSlice(dstSlice, srcSlice)
+					}
 					dst.SetMapIndex(key, dstSlice)
 				}
 			}
@@ -124,7 +140,7 @@ func deepMerge(dst, src reflect.Value, visited map[uintptr]*visit, depth int, co
 				continue
 			}
 
-			if srcElement.IsValid() && (overwrite || (!dstElement.IsValid() || isEmptyValue(dst))) {
+			if srcElement.IsValid() && (overwrite || (!dstElement.IsValid() || isEmptyValue(dstElement))) {
 				if dst.IsNil() {
 					dst.Set(reflect.MakeMap(dst.Type()))
 				}
@@ -137,7 +153,10 @@ func deepMerge(dst, src reflect.Value, visited map[uintptr]*visit, depth int, co
 		}
 		if !isEmptyValue(src) && (overwrite || isEmptyValue(dst)) && !config.AppendSlice {
 			dst.Set(src)
-		} else {
+		} else if config.AppendSlice {
+			if src.Type() != dst.Type() {
+				return fmt.Errorf("cannot append two slice with different type (%s, %s)", src.Type(), dst.Type())
+			}
 			dst.Set(reflect.AppendSlice(dst, src))
 		}
 	case reflect.Ptr:

vendor/github.com/imdario/mergo/mergo.go

@@ -45,7 +45,12 @@ func isEmptyValue(v reflect.Value) bool {
 		return v.Uint() == 0
 	case reflect.Float32, reflect.Float64:
 		return v.Float() == 0
-	case reflect.Interface, reflect.Ptr, reflect.Func:
+	case reflect.Interface, reflect.Ptr:
+		if v.IsNil() {
+			return true
+		}
+		return isEmptyValue(v.Elem())
+	case reflect.Func:
 		return v.IsNil()
 	case reflect.Invalid:
 		return true