[processing] fix broken stdout handling in GRASS algs (fix #21142)

python/plugins/processing/algs/grass7/Grass7Algorithm.py

@@ -631,15 +631,13 @@ class Grass7Algorithm(QgsProcessingAlgorithm):
                     if outName in parameters and parameters[outName] is not None:
                         # for HTML reports, we need to redirect stdout
                         if out.defaultFileExtension().lower() == 'html':
-                            command += ' > "{}"'.format(
-                                self.parameterAsFileOutput(
-                                    parameters, outName, context)
-                            )
+                            command += ' {}=- > "{}"'.format(
+                                outName,
+                                self.parameterAsFileOutput(parameters, outName, context))
                         else:
                             command += ' {}="{}"'.format(
                                 outName,
-                                self.parameterAsFileOutput(
-                                    parameters, outName, context))
+                                self.parameterAsFileOutput(parameters, outName, context))
                 # For folders destination
                 elif isinstance(out, QgsProcessingParameterFolderDestination):
                     # We need to add a unique temporary basename

python/plugins/processing/algs/grass7/description/v.net.salesman.txt

@@ -10,5 +10,5 @@ QgsProcessingParameterNumber|threshold|Threshold for connecting centers to the n
 *QgsProcessingParameterField|arc_backward_column|Arc backward direction cost column (number)|None|input|0|False|True
 *QgsProcessingParameterBoolean|-g|Use geodesic calculation for longitude-latitude locations|False|True
 QgsProcessingParameterVectorDestination|output|Network_Salesman
-QgsProcessingParameterFileDestination|sequence|Output file holding node sequence|Html files (*.html)|report.html|True
+QgsProcessingParameterFileDestination|sequence|Output file holding node sequence|CSV files (*.csv)|None|True
 

python/plugins/processing/tests/testdata/expected/grass7/v_net_salesman_seq.csv

@@ -0,0 +1,4 @@
+sequence;category;cost_to_next
+1;1;0.000
+2;2;0.000
+3;3;0.000

python/plugins/processing/tests/testdata/grass7_algorithms_vector_tests.yaml

@@ -280,6 +280,9 @@ tests:
       output:
         name: expected/grass7/v_net_salesman.shp
         type: vector
+      sequence:
+        name: expected/grass7/v_net_salesman_seq.csv
+        type: file
 
   - algorithm: grass7:v.net.steiner
     name: v.net.steiner