Do not reset the source directory if there is modification.

We simply do a `git merge --ff-only` instead of a `git reset`. This way:

- No change on the local repository
    => update to `remote/master`
- If you switch branch and local branch is behind `remote/master`
    => fast forward to `remote/master`
- If you switch branch and branches diverge
    => No update of the directory
- On branch master (or a branch behind `origin/master`) with compatible
  change in the working tree.
    =>  update of the directory
- On branch master (or a branch behind `origin/master`) but incompatible
  change in the working tree.
    =>  No update.

This way, sources are keep up-to-date as far as possible.

kiwixbuild/__init__.py

@@ -48,6 +48,10 @@ def parse_args():
                           help=("Specify the architecture to build for ios application/libraries.\n"
                                 "Can be specified several times to build for several architectures.\n"
                                 "If not specified, all architectures will be build."))
+    subgroup.add_argument('--fast-clone', action='store_true',
+                          help=("Do not clone the whole repository.\n"
+                                "This is useful for one shot build but it is not recommended if you want "
+                                "to develop with the cloned sources."))
     options = parser.parse_args()
 
     if not options.android_arch:

kiwixbuild/dependencies/base.py

@@ -3,7 +3,7 @@ import os
 import shutil
 import time
 
-from kiwixbuild.utils import pj, Context, SkipCommand, extract_archive, Defaultdict, StopBuild, run_command
+from kiwixbuild.utils import pj, Context, SkipCommand, WarningMessage, extract_archive, Defaultdict, StopBuild, run_command
 from kiwixbuild.versions import main_project_versions, base_deps_versions
 from kiwixbuild._global import neutralEnv, option
 
@@ -78,6 +78,8 @@ class Source:
             duration = time.time() - start_time
             print("OK ({:.1f}s)".format(duration))
             return ret
+        except WarningMessage as e:
+            print(e)
         except SkipCommand:
             print("SKIP")
         except subprocess.CalledProcessError:
@@ -152,22 +154,31 @@ class GitClone(Source):
         else:
             return self.base_git_ref
 
-    def _git_clone(self, context):
-        if os.path.exists(self.git_path):
-            raise SkipCommand()
-        command = "git clone --depth=1 --branch {} {} {}".format(
-            self.git_ref, self.git_remote, self.source_dir)
-        run_command(command, neutralEnv('source_dir'), context)
+    def _git_init(self, context):
+        if option('fast_clone'):
+            command = "git clone --depth=1 --branch {} {} {}".format(
+                self.git_ref, self.git_remote, self.source_dir)
+            run_command(command, neutralEnv('source_dir'), context)
+        else:
+            command = "git clone {} {}".format(self.git_remote, self.source_dir)
+            run_command(command, neutralEnv('source_dir'), context)
+            command = "git checkout {}".format(self.git_ref)
+            run_command(command, self.git_path, context)
 
     def _git_update(self, context):
-        command = "git fetch origin {}".format(
-            self.git_ref)
+        command = "git fetch origin {}".format(self.git_ref)
         run_command(command, self.git_path, context)
-        run_command("git checkout "+self.git_ref, self.git_path, context)
+        try:
+            command = "git merge --ff-only origin/{}".format(self.git_ref)
+            run_command(command, self.git_path, context)
+        except subprocess.CalledProcessError:
+            raise WarningMessage("Cannot update, please check log for information")
 
     def prepare(self):
-        self.command('gitclone', self._git_clone)
-        self.command('gitupdate', self._git_update)
+        if not os.path.exists(self.git_path):
+            self.command('gitinit', self._git_init)
+        else:
+            self.command('gitupdate', self._git_update)
         if hasattr(self, '_post_prepare_script'):
             self.command('post_prepare_script', self._post_prepare_script)
 
@@ -238,6 +249,8 @@ class Builder:
             return ret
         except SkipCommand:
             print("SKIP")
+        except WarningMessage as e:
+            print(e)
         except subprocess.CalledProcessError:
             print("ERROR")
             try:

kiwixbuild/utils.py

@@ -134,11 +134,7 @@ def download_remote(what, where):
         raise StopBuild("Sha 256 doesn't correspond")
 
 
-class SkipCommand(Exception):
-    pass
-
-
-class StopBuild(Exception):
+class BaseCommandResult(Exception):
     def __init__(self, msg=""):
         self.msg = msg
 
@@ -146,6 +142,22 @@ class StopBuild(Exception):
         return self.msg
 
 
+class SkipCommand(BaseCommandResult):
+    def __str__(self):
+        if self.msg:
+            return "SKIP : {}".format(self.msg)
+        return "SKIP"
+
+
+class WarningMessage(BaseCommandResult):
+    def __str__(self):
+        return "WARNING : {}".format(self.msg)
+
+
+class StopBuild(BaseCommandResult):
+    pass
+
+
 class Remotefile(namedtuple('Remotefile', ('name', 'sha256', 'url'))):
     def __new__(cls, name, sha256, url=None):
         if url is None: