Speed up git checkouts

Use shallow checkouts if .git folder is not required
Don't download submodules if we do that again for a potentially other version

Author: Flamefire

easybuild/tools/filetools.py

@@ -2471,11 +2471,17 @@ def get_source_tarball_from_git(filename, targetdir, git_config):
     # compose 'git clone' command, and run it
     clone_cmd = ['git', 'clone']
 
+    if not keep_git_dir:
+        # Speed up cloning by only fetching the most recent commit, not the whole history
+        # When we don't want to keep the .git folder there won't be a difference in the result
+        clone_cmd.extend(['--depth', '1'])
+
     if tag:
         clone_cmd.extend(['--branch', 'refs/tags/' + tag])
-
-    if recursive:
-        clone_cmd.append('--recursive')
+        if recursive:
+            clone_cmd.append('--recursive')
+    else:
+        clone_cmd.append('--no-checkout')  # We do that manually below
 
     clone_cmd.append('%s/%s.git' % (url, repo_name))
 

test/framework/filetools.py

@@ -2579,7 +2579,7 @@ def run_check():
             'tag': 'tag_for_tests',
         }
         expected = '\n'.join([
-            r'  running command "git clone --branch refs/tags/tag_for_tests [email protected]:easybuilders/testrepository.git"',
+            r'  running command "git clone --depth 1 --branch refs/tags/tag_for_tests [email protected]:easybuilders/testrepository.git"',
             r"  \(in .*/tmp.*\)",
             r'  running command "tar cfvz .*/target/test.tar.gz --exclude .git testrepository"',
             r"  \(in .*/tmp.*\)",
@@ -2588,7 +2588,7 @@ def run_check():
 
         git_config['recursive'] = True
         expected = '\n'.join([
-            r'  running command "git clone --branch refs/tags/tag_for_tests --recursive [email protected]:easybuilders/testrepository.git"',
+            r'  running command "git clone --depth 1 --branch refs/tags/tag_for_tests --recursive [email protected]:easybuilders/testrepository.git"',
             r"  \(in .*/tmp.*\)",
             r'  running command "tar cfvz .*/target/test.tar.gz --exclude .git testrepository"',
             r"  \(in .*/tmp.*\)",
@@ -2608,7 +2608,7 @@ def run_check():
         del git_config['tag']
         git_config['commit'] = '8456f86'
         expected = '\n'.join([
-            r'  running command "git clone --recursive [email protected]:easybuilders/testrepository.git"',
+            r'  running command "git clone --depth 1 --no-checkout [email protected]:easybuilders/testrepository.git"',
             r"  \(in .*/tmp.*\)",
             r'  running command "git checkout 8456f86 && git submodule update --init --recursive"',
             r"  \(in testrepository\)",
@@ -2619,7 +2619,7 @@ def run_check():
 
         del git_config['recursive']
         expected = '\n'.join([
-            r'  running command "git clone [email protected]:easybuilders/testrepository.git"',
+            r'  running command "git clone --depth 1 --no-checkout [email protected]:easybuilders/testrepository.git"',
             r"  \(in .*/tmp.*\)",
             r'  running command "git checkout 8456f86"',
             r"  \(in testrepository\)",