don't delete downloaded files in certain edge cases

gallery_dl/downloader/common.py

@@ -15,6 +15,9 @@ class BasicDownloader():
 
     max_tries = 5
 
+    def __init__(self):
+        self.downloading = False
+
     def download(self, url, pathfmt):
         """Download the resource at 'url' and write it to a file-like object"""
         try:
@@ -22,7 +25,8 @@ class BasicDownloader():
         except:
             # remove file if download failed
             try:
-                os.unlink(pathfmt.realpath)
+                if self.downloading:
+                    os.unlink(pathfmt.realpath)
             except (AttributeError, FileNotFoundError):
                 pass
             raise

gallery_dl/downloader/http.py

@@ -61,9 +61,11 @@ class Downloader(BasicDownloader):
                 return
 
         self.out.start(pathfmt.path)
+        self.downloading = True
         with pathfmt.open() as file:
             for data in response.iter_content(16384):
                 file.write(data)
+        self.downloading = False
         self.out.success(pathfmt.path, tries)
 
     def set_headers(self, headers):

gallery_dl/downloader/text.py

@@ -24,6 +24,8 @@ class Downloader(BasicDownloader):
                 return
 
         self.out.start(pathfmt.path)
+        self.downloading = True
         with pathfmt.open() as file:
             file.write(bytes(url[7:], "utf-8"))
+        self.downloading = False
         self.out.success(pathfmt.path, 0)