osgeo4w: rely on GRASS' GISBASE environment variable instead of

detecting the path (ie. use the same version for processing as the
version that the grass plugin uses)

(cherry picked from commit 806ae86)

python/plugins/processing/algs/grass7/Grass7Utils.py

@@ -133,9 +133,6 @@ def grassBin():
         Find GRASS binary path on the operating system.
         Sets global variable Grass7Utils.command
         """
-        cmdList = ["grass76", "grass74", "grass72", "grass70", "grass",
-                   "grass76.sh", "grass74.sh", "grass72.sh", "grass70.sh", "grass.sh"]
-
         def searchFolder(folder):
             """
             Inline function to search for grass binaries into a folder
@@ -154,6 +151,24 @@ def searchFolder(folder):
         path = Grass7Utils.grassPath()
         command = None
 
+        vn = os.path.join(path, "etc", "VERSIONNUMBER")
+        if os.path.isfile(vn):
+            with open(vn, "r") as f:
+                major, minor, patch = f.readlines()[0].split(' ')[0].split('.')
+                if patch != 'svn':
+                    patch = ''
+                cmdList = [
+                    "grass{}{}{}".format(major, minor, patch),
+                    "grass",
+                    "grass{}{}{}.sh".format(major, minor, patch),
+                    "grass.sh"
+                ]
+        else:
+            cmdList = [
+                "grass76", "grass74", "grass72", "grass70", "grass",
+                "grass76.sh", "grass74.sh", "grass72.sh", "grass70.sh", "grass.sh"
+            ]
+
         # For MS-Windows there is a difference between GRASS Path and GRASS binary
         if isWindows():
             # If nothing found, use OSGEO4W or QgsPrefix:
@@ -167,7 +182,7 @@ def searchFolder(folder):
             # Search in grassPath
             command = searchFolder(path)
 
-        # Under GNU/Linux or if everything has failed, use shutil
+        # If everything has failed, use shutil
         if not command:
             for cmd in cmdList:
                 testBin = shutil.which(cmd)
@@ -204,15 +219,14 @@ def grassPath():
         if folder is None:
             # Under MS-Windows, we use OSGEO4W or QGIS Path for folder
             if isWindows():
-                if "OSGEO4W_ROOT" in os.environ:
-                    testfolder = os.path.join(str(os.environ['OSGEO4W_ROOT']), "apps")
+                if "GISBASE" in os.environ:
+                    folder = os.environ["GISBASE"]
                 else:
-                    testfolder = str(QgsApplication.prefixPath())
-                testfolder = os.path.join(testfolder, 'grass')
-                if os.path.isdir(testfolder):
-                    grassfolders = sorted([f for f in os.listdir(testfolder) if f.startswith("grass-7.") and os.path.isdir(os.path.join(testfolder, f))], reverse=True, key=lambda x: [int(v) for v in x[len("grass-"):].split('.') if v != 'svn'])
-                    if grassfolders:
-                        folder = os.path.join(testfolder, grassfolders[0])
+                    testfolder = os.path.join(str(QgsApplication.prefixPath()), 'grass')
+                    if os.path.isdir(testfolder):
+                        grassfolders = sorted([f for f in os.listdir(testfolder) if f.startswith("grass-7.") and os.path.isdir(os.path.join(testfolder, f))], reverse=True, key=lambda x: [int(v) for v in x[len("grass-"):].split('.') if v != 'svn'])
+                        if grassfolders:
+                            folder = os.path.join(testfolder, grassfolders[0])
             elif isMac():
                 # For MacOSX, we scan some well-known directories
                 # Start with QGIS bundle