fix: allow mailmaps to change the email by name and email (#1417)

Author: Byron

gix-mailmap/src/entry.rs

@@ -25,22 +25,24 @@ impl<'a> Entry<'a> {
 /// Constructors indicating what kind of mapping is created.
 ///
 /// Only these combinations of values are valid.
-#[allow(missing_docs)]
 impl<'a> Entry<'a> {
+    /// An entry that changes the name by an email.
     pub fn change_name_by_email(proper_name: impl Into<&'a BStr>, commit_email: impl Into<&'a BStr>) -> Self {
         Entry {
             new_name: Some(proper_name.into()),
             old_email: commit_email.into(),
             ..Default::default()
         }
     }
+    /// An entry that changes the email by an email.
     pub fn change_email_by_email(proper_email: impl Into<&'a BStr>, commit_email: impl Into<&'a BStr>) -> Self {
         Entry {
             new_email: Some(proper_email.into()),
             old_email: commit_email.into(),
             ..Default::default()
         }
     }
+    /// An entry that changes the email by a name and email.
     pub fn change_email_by_name_and_email(
         proper_email: impl Into<&'a BStr>,
         commit_name: impl Into<&'a BStr>,
@@ -53,6 +55,7 @@ impl<'a> Entry<'a> {
             ..Default::default()
         }
     }
+    /// An entry that changes a name and the email by an email.
     pub fn change_name_and_email_by_email(
         proper_name: impl Into<&'a BStr>,
         proper_email: impl Into<&'a BStr>,
@@ -65,7 +68,7 @@ impl<'a> Entry<'a> {
             ..Default::default()
         }
     }
-
+    /// An entry that changes a name and email by a name and email.
     pub fn change_name_and_email_by_name_and_email(
         proper_name: impl Into<&'a BStr>,
         proper_email: impl Into<&'a BStr>,

gix-mailmap/src/parse.rs

@@ -77,6 +77,9 @@ fn parse_line(line: &BStr, line_number: usize) -> Result<Entry<'_>, Error> {
         (Some(proper_name), Some(proper_email), Some(commit_name), Some(commit_email)) => {
             Entry::change_name_and_email_by_name_and_email(proper_name, proper_email, commit_name, commit_email)
         }
+        (None, Some(proper_email), Some(commit_name), Some(commit_email)) => {
+            Entry::change_email_by_name_and_email(proper_email, commit_name, commit_email)
+        }
         _ => {
             return Err(Error::Malformed {
                 line_number,