Never catch all exceptions

It was eaching KeyboardInterrupt and causing me grief.
(A small exception is granted for a case that does cleanup and re-raises
te exception.)

csppfetch/__init__.py

@@ -42,7 +42,7 @@ def logprogress(msg):
     try:
         logging.progress(msg)
         return
-    except:
+    except Exception:
         pass
     logging.info(msg)
 
@@ -367,7 +367,7 @@ def download_all(url_to_dst, download_stats, do_download, timeout):
                 download_to_file_no_lock(url, path, file, timeout)
                 download_successful("download_all success", path, atomic.final_size(), download_stats)
 
-        except:
+        except: # We're going to re-raise the exception.
             # Files present at start should not be in todo, so this is just
             # stuff we might have downloaded. Wipe it out, as it's all or
             # nothing
@@ -838,7 +838,7 @@ class Downloader:
                         try:
                             logging.debug("Data set successfully acquired. Problems encountered and resolved:")
                             dump_problems(logging.debug, problems)
-                        except:
+                        except Exception:
                             # Don't cause grief over logging problems here
                             # since any exceptions will retry downloads
                             # when we already have the files!
@@ -859,7 +859,7 @@ class Downloader:
 
         try:
             first = problems[0][0]
-        except:
+        except IndexError:
             first = ""
         raise DownloadsFailedException("Errors occurred during download, including "+first)
 
@@ -940,7 +940,7 @@ class Downloader:
             try:
                 self.download_first_available(filesets, dst, timeout=timeout, retries=1, retry_wait=1, download_stats = download_stats)
 
-            except:
+            except Exception:
                 # We just keep trucking on; missed files are unfortunate,
                 # but not much we can do.
                 pass

csppfetch/exclusivelockfile.py

@@ -74,7 +74,7 @@ class ExclusiveLockFile:
             self.file = None
             self.filename = filename_or_file
             logger.debug(f"ExclusiveLockFile({filename_or_file}) is path-like")
-        except:
+        except Exception:
             # Not Path-like? I hope it's file-like
             self.file = filename_or_file
             self.filename = None
@@ -233,7 +233,7 @@ def unlink_if_possible(filename):
     try:
         os.unlink(filename)
         return True
-    except:
+    except OSError:
         return False
 
 class AtomicCreateIfMissing:

csppfetch/roundtozero.py

@@ -42,11 +42,11 @@ def roundtozero(value, step = None, offset = None):
     """
     try:
         if step is None: step = type(value)(1)
-    except:
+    except Exception:
         raise ValueError("roundtozero: Unable to construct a default step using type(value)(1); you'll need to pass step is explicitly.")
     try:
         if offset is None: offset = type(value)()
-    except:
+    except Exception:
         raise ValueError("roundtozero: Unable to construct a default step using type(value)(); you'll need to pass step is explicitly.")
 
     offset_value = value - offset